Mattermost Server
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Incorrect authorization in Mattermost's Boards component across versions 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 enables privilege escalation within board management. Board editors and non-guest team members can supply arbitrary values in BoardMember.Scheme* fields through the boards member API or archive-import endpoint, effectively granting board admin rights to any user without server-side enforcement. No public exploit has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Authenticated Mattermost users can degrade message post-processing latency for every member of the channels they share by storing an oversized list of custom mention keywords (notify_props.mention_keys) on their own profile, which the server then matches against each post. Because the matching routine scales quadratically and multibyte/Unicode keywords add per-character cost, and neither the number nor the size of stored keywords is capped, each post the attacker's channel peers send or receive is processed far more expensively on the attacker's behalf. Impact is confined to availability degradation (CVSS 4.3, AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L; CWE-770); no data exposure or crash is involved, valid authentication plus at least one shared channel is required, and no public exploit has been identified at time of analysis.
Information disclosure in Mattermost release lines 11.7.x, 11.8.x, 11.9.x and 11.10.x (up to 11.7.10, 11.8.5, 11.9.1 and 11.10.1 respectively) allows an authenticated user to learn the channel ID of a private channel that another user is actively viewing. The user status API endpoints return an unsanitized active-channel field, so any provisioned account on the same server - with no membership in the target private channel, which is precisely the flaw - can query another user's status and observe which private channel that user is currently reading. The exposure is limited to the channel identifier itself, not its contents, name or membership, but it still reveals the existence of private channels and correlates named users with sensitive collaboration spaces. Rated CVSS 4.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N), this is a low-to-moderate urgency issue rather than an emergency, and no public exploit has been identified at time of analysis.
Mattermost 11.7.x through 11.10.x fails to invalidate the stored AD/LDAP bind password whenever other connection settings - such as the directory server address - are changed in the System Console, so the previously saved plaintext credential is carried over to the new configuration. An authenticated System Console administrator (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N, base 4.9) can then trigger the LDAP Test Connection / diagnostics feature, which transmits that retained plaintext bind password to the configured server address, potentially an attacker-controlled host set by the same admin. There is confirmed no CISA KEV entry and no public exploit identified at time of analysis, and no EPSS score was supplied; exploitation is gated behind high-privilege System Console access, an existing AD/LDAP integration with a stored bind password, and the deliberate admin action of pointing the connection at a hostile host, making this a genuine but moderate-priority confidentiality issue rather than an emergency.
Mattermost Server versions 11.7.x through 11.10.x can disclose the stored client secret of an outgoing OAuth connection to an attacker who holds the administrative permission to manage those connections. The platform fails to require re-entry of the stored secret during connection validation, so an authenticated high-privileged user can repoint the connection's token URL at an attacker-controlled endpoint and trigger validation, causing the secret to be sent to that endpoint (CWE-201, information disclosure). Our assessment rates this CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N), with the practical risk tempered by the privilege prerequisite - the feature must be enabled and at least one outgoing OAuth connection with a stored secret must already exist; no public exploit was identified at time of analysis and there is no KEV listing. Exploitation is remote, requires no victim interaction, and yields confidentiality impact only (no integrity or availability impact).
Authenticated users on Mattermost Server 11.7.x through 11.10.0 can quarantine posts inside direct and group messages they are not participants of by issuing a direct API call to the post-quarantine endpoint, because the server performs no DM/GM membership or authorization check before processing the request (CWE-862, Missing Authorization). The flaw is remotely reachable over the network but requires a valid low-privileged account (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L per the assessed vector), and the realistic impact is improper manipulation of the moderation/quarantine state of DM and GM posts rather than disclosure of message contents or full data compromise. There is no public exploit identified at time of analysis and no confirmed active exploitation (no CISA KEV entry); this is a moderate-severity authorization weakness that Mattermost tracks under advisory MMSA-2026-00756.
Authenticated guest accounts on Mattermost 11.7.x through 11.7.9, 11.8.x through 11.8.5, 11.9.x through 11.9.1, and 11.10.0 can be escalated to team or channel administrator by abusing the member roles API endpoint, which fails to validate a crafted combination of guest and admin scheme roles. The flaw requires only a valid guest login and network reachability to the API, so any server that provisions guest accounts is exposed, though no public exploit code or confirmed active exploitation has been identified at time of analysis. Vendor advisory MMSA-2026-00752 tracks the issue, and Mattermost has published it on its security updates page.
Mattermost's data retention teams API endpoint fails to sanitize returned Team objects, exposing private teams' secret `invite_id` and email fields to any authenticated user holding only the read-only Data Retention Policy permission. An attacker exploiting CVE-2026-91181 can call `GET /api/v4/data_retention/policies/{policy_id}/teams`, harvest the `invite_id` of private teams they have no membership in, and use it to join those teams without authorization - effectively achieving lateral movement across private channels and communications. No public exploit code has been identified and the vulnerability is not listed in CISA KEV at time of analysis.
Incorrect authorization in Mattermost Boards allows an authenticated board editor to relink any editable board to an arbitrary channel by exploiting a missing PermissionManageBoardRoles check on the channelId field of the batch endpoint. Affected are Mattermost versions 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 (advisory MMSA-2026-00686). No public exploit code or CISA KEV listing has been identified at time of analysis, but the low attack complexity and network accessibility make this straightforward to execute for any authenticated board editor.
Denial of service in Mattermost's Boards (focalboard) plugin allows any authenticated user to crash the plugin process and disrupt Boards availability for all users on the instance by sending a single malformed WebSocket message. The root cause is absent input validation on the teamId field type in custom_focalboard_SUBSCRIBE_TEAM WebSocket commands, classified under CWE-704 (Incorrect Type Conversion). Affected versions span 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3; no public exploit has been identified at time of analysis.
Privilege escalation in Mattermost's channel administration API allows authenticated channel administrators to assign non-channel-scoped roles to channel members, exceeding their intended authorization boundary. Three active release lines are affected: 10.11.x through 10.11.21, 11.7.x through 11.7.6, and 11.8.x through 11.8.2. No public exploit code has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Private channel membership disclosure in Mattermost's Boards feature allows any authenticated team member to enumerate who belongs to private channels they are not authorized to view. Affected across three concurrently maintained release trains - 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 - the flaw is exploitable by any valid team account via standard board management API calls. No public exploit or active exploitation has been identified at time of analysis; the CVSS score of 4.3 (PR:L, C:L) accurately reflects the limited but real confidentiality impact, particularly meaningful in regulated environments where private channel membership itself is sensitive.
Mattermost's Playbooks feature in versions 11.7.x through 11.7.6 and 10.11.x through 10.11.21 omits run-state enforcement on API write operations, allowing any authenticated run participant to alter completed playbook runs via REST and GraphQL endpoints. An attacker with low privileges can overwrite status, checklists, retrospective content, ownership, and participant lists on runs that should be immutable once finished, undermining post-incident audit integrity. No public exploit has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Incorrect authorization in Mattermost's OAuth and personal access token management endpoints allows an OAuth application holding a delegated user token to call account-management endpoints beyond its intended scope, revoking the victim user's authorizations or tokens for unrelated integrations. Affected are Mattermost 11.7.0 through 11.7.6 and 10.11.0 through 10.11.21. No public exploit code has been identified and this vulnerability is not listed in the CISA KEV catalog, though the low-complexity, network-accessible nature of the flaw makes it straightforward to abuse for any actor who has legitimately obtained an OAuth delegated token.
Privilege escalation in Mattermost's Boards feature allows a low-privileged board member to elevate a guest user to Board Admin by importing a specially crafted .boardarchive file. Affected are Mattermost versions 10.11.0 through 10.11.21 and 11.7.0 through 11.7.6. No public exploit or KEV listing has been identified, but the low attack complexity and the insider-threat profile make this a meaningful risk in multi-tenant or externally-collaborative Mattermost deployments.
Incorrect authorization in Mattermost's ABAC policy unassign API endpoint allows an authenticated team administrator to remove attribute-based access control policy assignments from channels that no longer belong to their team. Affected releases are Mattermost 11.7.0 through 11.7.6 and 11.8.0 through 11.8.3, tracked as MMSA-2026-00718 (ENISA EUVD-2026-60212). The exploit window opens when a channel is migrated between teams and the endpoint fails to re-verify team membership before executing the unassignment, letting a malicious admin modify access-control policy state beyond their administrative boundary.
Privilege retention in Mattermost Boards allows a user demoted to System Guest to continue exercising Board Admin privileges via the Boards REST API or UI. Affected are Mattermost versions 11.7.0-11.7.6, 10.11.0-10.11.21, and 11.8.0-11.8.3, where the SchemeAdmin flag is not reconciled against the user's current role during or after demotion. An authenticated attacker in this state can invoke admin-only Boards operations - including modifying board permissions and settings - without detection by role-based access checks. No public exploit code is identified and no CISA KEV listing is present at time of analysis.
Server-side request forgery in the Mattermost Agents plugin MCP server (stdio mode) allows a low-privileged local attacker to make the server fetch arbitrary internal URLs submitted as file attachment references in post creation requests, enabling exfiltration of data from RFC 1918-addressed services on the internal network. Affected are Mattermost deployments running versions 10.11.x ≤ 10.11.18, 11.5.x ≤ 11.5.6, and 11.6.x ≤ 11.6.3 with the Agents plugin's MCP server active in stdio mode. No public exploit code or CISA KEV listing is present in the available data; exploitation is constrained to attackers who already have local access to the stdio MCP interface.
Markdown image rendering restrictions in Mattermost are bypassed specifically for AI bot tool result posts, enabling authenticated attackers to exfiltrate data to attacker-controlled infrastructure. Affected are Mattermost versions 10.11.x through 10.11.18, 11.5.x through 11.5.6, and 11.6.x through 11.6.3. When a victim's client renders an AI bot tool result post containing injected markdown image syntax, the client issues an outbound request to the attacker's server, leaking request metadata such as session tokens or channel context. No public exploit code exists and this vulnerability is not listed in the CISA KEV catalog at time of analysis.
Mattermost Server versions 11.3.0, 11.2.x through 11.2.2, and 10.11.x through 10.11.10 contain a server-side request forgery (SSRF) vulnerability due to improper validation of IPv4-mapped IPv6 addresses, allowing authenticated attackers to bypass reserved IP restrictions and access internal services. An attacker with login credentials can craft requests using IPv6 notation (such as [::ffff:127.0.0.1]) to reach localhost or other restricted internal endpoints that would normally be blocked. No patch is currently available for this vulnerability.
A remote code execution vulnerability (CVSS 4.3) that allows guest users without read permissions. Remediation should follow standard vulnerability management procedures.
CVE-2026-22545 is a security vulnerability (CVSS 3.1) that allows an authenticated attacker. Remediation should follow standard vulnerability management procedures.
CVE-2026-21386 is a security vulnerability (CVSS 4.3) that allows an authenticated team member. Remediation should follow standard vulnerability management procedures.
Mattermost versions 10.11.x <= 10.11.9 fail to enforce invite permissions when updating team settings, which allows team administrators without proper permissions to bypass restrictions and add users to their team via API requests. Mattermost Advisory ID: MMSA-2025-00561 [CVSS 3.8 LOW]
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate team membership when processing channel mentions which allows authenticated users to determine the existence of teams and their URL names via posting channel shortlinks and observing the channel_mentions property in the API response. [CVSS 4.3 MEDIUM]
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. [CVSS 5.7 MEDIUM]
Mattermost Server versions 11.1.x through 11.1.2, 10.11.x through 10.11.9, and 11.2.x through 11.2.1 inadequately enforce login method restrictions, permitting authenticated users to circumvent SSO-only requirements by authenticating with a userID instead. This allows an attacker with valid credentials to gain unauthorized access to accounts restricted to single sign-on authentication. No patch is currently available for this vulnerability.
Insufficient identity validation in Mattermost Server (versions 11.1.x through 11.2.1 and earlier) and Zoom Plugin (versions up to 1.11.0) allows authenticated users to initiate Zoom meetings as arbitrary users and modify other users' posts through direct API manipulation. An attacker with valid credentials can exploit the /api/v1/askPMI endpoint to impersonate other users and alter post content without proper authorization checks. The vulnerability affects multiple Mattermost and plugin versions with no patch currently available.
Mattermost and Zoom plugin versions fail to properly authenticate users before allowing modifications to Zoom meeting restrictions, enabling any logged-in user to alter meeting settings across arbitrary channels. Affected versions include Mattermost 11.1.x through 11.1.2, 10.11.x through 10.11.9, 11.2.x through 11.2.1, and Zoom plugin versions up to 1.11.0. No patch is currently available for this privilege escalation vulnerability.
Mattermost versions 11.1.2, 10.11.9, and 11.2.1 and earlier fail to properly enforce access controls in the Jira plugin's /create-issue API endpoint, allowing authenticated users to read restricted post content and attachments from channels they cannot access by referencing post IDs. An attacker with Jira plugin access can exploit this to enumerate and exfiltrate sensitive information from private or restricted channels. No patch is currently available for affected versions.
Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549 [CVSS 3.1 LOW]
Mattermost versions 10.11.x <= 10.11.8, 11.1.x <= 11.1.1, 11.0.x <= 11.0.6 fail to prevent infinite re-renders on API errors which allows authenticated users to cause application-level DoS via triggering unbounded component re-render loops. [CVSS 6.8 MEDIUM]
Mattermost versions 10.11.x <= 10.11.8 fail to validate input size before processing hashtags which allows an authenticated attacker to exhaust CPU resources via a single HTTP request containing a post with thousands space-separated tokens [CVSS 3.1 LOW]
Incorrect authorization in Mattermost Server lets any authenticated user forge a '/share-issue-publicly' post action, so that when a victim user interacts with the crafted post, Jira ticket content the victim is authorized to see is relayed to the attacker. Affected lines are 10.11.x through 10.11.7, 10.12.x through 10.12.3, 11.0.x through 11.0.5, and 11.1.x through 11.1.0, and exploitation requires the Jira plugin to be installed, an account able to post into a channel the victim reads, and victim interaction (CVSS 3.1 4.1, AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N). No public exploit code and no confirmed active exploitation were identified at time of analysis, and the exposure is limited to Jira ticket data rather than server compromise.
Mattermost Server versions 10.11.x through 11.1.0 contain an authorization bypass in the Jira plugin's post-to-comment feature that lets an authenticated user read posts and attachments from channels they are not allowed to access. Exploitation requires a valid Mattermost account and an enabled/configured Jira integration where posts can be attached as Jira comments, with impact limited to confidentiality of exposed post content; no public exploit identified at time of analysis. The CVSS 3.1 score of 4.3 reflects a moderate issue rather than a high-severity breach.
Improper authentication enforcement in the Mattermost Jira plugin lets an unauthenticated attacker who knows a valid Mattermost user ID send crafted plugin payloads that spoof that user and inject arbitrary Jira issue-key paths, causing the plugin to issue authenticated GET and POST requests to the connected Jira server. The flaw affects Mattermost Server 11.1.x through 11.1.0, 11.0.x through 11.0.5, 10.12.x through 10.12.3, and 10.11.x through 10.11.7, but only when the Jira plugin (versions <= 4.4.0) is installed, enabled, and connected to Jira; default installations without the Jira integration are not exposed. Per the CVSS vector the attack is unauthenticated and needs no user interaction, and the decisive practical barrier is that the attacker must possess or guess a usable Mattermost user ID. No confirmed active exploitation has been reported (not in CISA KEV) and no public exploit code has been identified; EPSS is low at 0.26% (17th percentile), so this is a mid-tier priority rather than an emergency. Mattermost Advisory ID: MMSA-2025-00555.
Mattermost Server versions 10.11.x through 10.12.2 fail to invalidate remote cluster invite tokens when using the legacy (v1) protocol or when the confirming party omits a refreshed token, allowing an attacker who has obtained a valid invite token to authenticate as the remote cluster and perform limited actions on shared channels. The vulnerability is rated low severity (CVSS 3.7) with an EPSS of 0.20%, and no public exploit or active exploitation has been reported.
Denial of service in Mattermost Server affects versions 11.0.x through 11.0.4, 10.12.x through 10.12.2, and 10.11.x through 10.11.6 when the Calls plug-in is enabled: a malformed WebSocket request field that is not valid UTF-8 is not rejected, causing the Calls plug-in to crash. The attacker must be an authenticated, low-privilege user (CVSS vector PR:L) capable of opening a WebSocket connection to the server, and the impact is limited to availability of the calling functionality with no data exposure or code execution. Severity is medium (CVSS 6.5, C:N/I:N/A:H); EPSS is 0.29% (20th percentile) and no public exploit identified at time of analysis - this is a medium-severity availability issue, not a top-tier priority.
Open redirect in Mattermost Server 10.11.x through 10.11.4 (CVE-2025-62690) allows unauthenticated remote attackers to redirect victims to arbitrary external sites by crafting a link to the /error endpoint that fails to validate the redirect URL. The attack requires the victim to open the link in a new tab (user interaction), and it enables phishing or credential harvesting rather than server compromise. No public exploit code or active exploitation has been identified, and the EPSS score is 0.15% (4th percentile), indicating low likelihood of exploitation.
Cross-site request forgery in the Mattermost Calls widget page allows an attacker to initiate calls and inject messages into channels or direct messages as a logged-in victim who is lured to a malicious webpage or crafted link. Affected deployments are Mattermost Server 11.0.x through 11.0.4, 10.12.x through 10.12.2, and 10.11.x through 10.11.6, plus Mattermost Calls plugin versions 1.10.0 and earlier; instances not running the Calls feature are not exposed. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N, score 4.3) confirms the attack is network-reachable with no attacker-side privileges but requires victim interaction, and impact is limited to low-integrity actions with no confidentiality or availability loss. No public exploit identified at time of analysis, and EPSS is 0.12% (2nd percentile), indicating low predicted exploitation activity; the flaw is a genuine but low-urgency medium-severity issue.
Reaction forwarding in the Mattermost GitHub plugin (versions <= 2.4.0) running on Mattermost Server 10.11.x (<= 10.11.6) fails to validate the plugin bot identity, letting an authenticated low-privilege user post crafted notification messages that cause another user to add reactions to arbitrary GitHub objects. The impact is limited to integrity (spoofed reactions on third-party GitHub content) with no confidentiality or availability loss, and exploitation requires high attack complexity plus victim interaction. EPSS is 0.18% (6th percentile), there is no CISA KEV entry, and no public exploit code was identified at time of analysis, so this is a low-priority, non-actively-exploited issue.
Access-control weakness in Mattermost Server 10.5.x through 10.5.12 and 10.11.x through 10.11.4 allows an authenticated user to retrieve files from Boards they are not a member of and to subscribe to blocks on inaccessible boards when they know the relevant identifiers. The issue is confidentiality-only (CVSS 4.3, C:L) and requires a valid account (PR:L), so it is not an anonymous authentication bypass despite the 'Authentication Bypass' tag. No public exploit identified at time of analysis and EPSS is very low (0.04%, 12th percentile); vendor patch is available.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to validate user permissions when deleting comments in Boards, which allows an authenticated user with the editor role to delete comments created by other users.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to sanitize team email addresses to be visible only to Team Admins, which allows any authenticated. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to enforce access permissions on the Agents plugin which allows other users to determine when users had read channels via channel member. Rated low severity (CVSS 3.0), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to sanitize user data which allows system administrators to access password hashes and MFA secrets via the POST. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost Server releases before version 11 do not enforce multi-factor authentication on the WebSocket connection path, so an unauthenticated remote attacker who can reach the server's WebSocket endpoint can receive sensitive information carried in WebSocket events even when the deployment relies on MFA for its HTTP login flow. Because the flaw is a missing-auth-check on a separate protocol channel rather than a credential compromise, no privileges or user interaction are required (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), but impact is limited to confidentiality - no modification or disruption. EPSS is low at 0.15% (36th percentile) and no public exploit code or CISA KEV entry was identified at time of analysis, so this is a genuine but moderate-priority issue rather than a top-tier emergency; exposure is concentrated on internet-reachable instances that actually use MFA, and is moot on deployments that do not rely on MFA.
Mattermost versions <11.0 fail to properly enforce the "Allow users to view archived channels" setting which allows regular users to access archived channel content and files via the "Open in. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost Server 10.11.x through 10.11.1, 10.10.x through 10.10.2, and 10.5.x through 10.5.10 allows an authenticated low-privileged user to join any team despite join restrictions by manipulating the RelayState value in the invite-token flow. The root cause is a missing authorization check (CWE-862) that fails to verify the user's permission to join the team associated with the original invite token. No public exploit identified at time of analysis, but the CVSS 8.1 rating reflects high confidentiality and integrity impact from unauthorized team access; exploitation requires a valid account on the target server.
Mattermost Server 10.11.x through 10.11.1, 10.10.x through 10.10.2, and 10.5.x through 10.5.10 contains a missing authorization flaw that allows an authenticated user to bypass team-join restrictions by manipulating the OAuth state parameter so the server reuses the original invite token without rechecking permissions. This lets an attacker with a valid account join teams they should not access, with high confidentiality and integrity impact but no availability impact. No public exploit identified at time of analysis; exploitation depends on a valid account and an OAuth-based join flow that carries the invite token in state.
Mattermost Server 10.5.x through 10.5.10 and 10.11.x through 10.11.2 uses non-constant-time comparisons when validating Cloud API keys and OAuth client secrets, creating a timing side channel that could theoretically let remote, unauthenticated attackers recover those secrets byte by byte through repeated response-time measurements. The high attack complexity reflects the need for precise, high-volume timing measurements against stable low-latency endpoints without rate limiting or timing noise; only those two secret-validation paths are affected, and no public exploit code or confirmed active exploitation was identified at time of analysis. EPSS is low at 0.27 percent (18th percentile), consistent with a low-priority information disclosure issue.
Mattermost Server 10.5.x through 10.5.10, 10.10.x through 10.10.2, and 10.11.x through 10.11.2 does not validate email ownership during the Slack import workflow, allowing an attacker who can supply import data to create verified accounts under arbitrary email domains and bypass email-domain-based team access restrictions. The flaw is a missing-authorization issue (CWE-862) rated CVSS 5.4 with a PR:L vector, though Slack import is generally a team or system admin function, so the practical privilege barrier may be higher than PR:L suggests. No public exploit code or CISA KEV entry is identified at time of analysis, and EPSS is low at 0.30% (22nd percentile).
Guest users on Mattermost Server 10.5.x through 10.5.10 and 10.11.x through 10.11.2 can bypass channel-membership authorization by calling the /api/v4/channels/{channel_id}/members endpoint, adding arbitrary team members to private channels they belong to. The flaw is an incorrect authorization check (CWE-863) scored CVSS 4.3 as an authenticated, network-reachable issue with low confidentiality impact and no integrity or availability effect. Exploitation requires a provisioned guest account and the guest feature in use, limiting realistic exposure to insiders or compromised guest credentials; EPSS is 0.33% (24th percentile), no public exploit code or CISA KEV entry was identified at time of analysis, and Mattermost has published patched releases.
Information disclosure in Mattermost Server 10.5.x through 10.5.12 and 10.11.x through 10.11.2 allows authenticated guest users to enumerate active public channels and their metadata via the /api/v4/teams/{team_id}/channels/ids endpoint. The issue is a missing-authorization condition in guest permission checks; exploitation requires a valid guest account, guest access enabled, and membership in the relevant team, and is limited to public-channel identifiers and metadata with no message content, write access, or availability impact. No public exploit code was identified at time of analysis, and EPSS is low at 0.31% (22nd percentile), making this a low-to-moderate severity information-disclosure issue rather than an emergency.
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate access controls which allows any authenticated user to download sensitive files via board file download endpoint. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost Server versions 10.8.x through 10.8.3, 10.5.x through 10.5.8, 9.11.x through 9.11.17, 10.10.x through 10.10.1, and 10.9.x through 10.9.3 contain a path-traversal weakness that lets an authenticated system administrator achieve remote code execution by configuring an unvalidated import directory path and uploading a malicious plugin to the prepackaged plugins directory. The attacker must already hold the high-privilege admin role, so the practical risk is concentrated in malicious insiders, compromised admin sessions, or post-exploitation chains rather than unauthenticated external attacks. At time of analysis, no public exploit identified at time of analysis, and EPSS is low at 0.03% (10th percentile); patch availability is confirmed per vendor advisory.
Mattermost versions 10.5.x <= 10.5.9 fail to properly validate redirect URLs which allows attackers to redirect users to malicious sites via crafted OAuth login URLs. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
Mattermost versions 10.10.x <= 10.10.1, 10.5.x <= 10.5.9, 10.9.x <= 10.9.4 fail to validate the redirect_to parameter, allowing an attacker to craft a malicious link that, once a user authenticates. Rated high severity (CVSS 7.6), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to properly validate cache keys for link metadata which allows authenticated users. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to sanitize file names which allows users with file upload permission to overwrite file attachment. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Members to Guests via the. Rated low severity (CVSS 3.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.8 fail to validate access controls at time of access which allows user to read a thread via AI posts. Rated low severity (CVSS 3.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2, 10.10.x <= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fail to sanitize the team invite ID in the POST /api/v4/teams/:teamId/restore endpoint which allows an team. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost Server versions 10.5.x <= 10.5.9 utilizing the Agents plugin fail to reject empty request bodies which allows users to trick users into clicking malicious links via post actions. Rated low severity (CVSS 3.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive information about linked private channels including channel name, display name, and participant count through the run metadata API endpoint.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly enforce channel member management permissions when adding participants to playbook runs. This allows authenticated users with member-level permissions to bypass system admin restrictions and add or remove users to/from private channels via the playbook run participants feature, even when the 'Manage Members' permission has been explicitly removed. This can lead to unauthorized access to sensitive channel content and allow guest users to gain channel management privileges.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly retrieve requestorInfo from playbooks handler for guest users which allows an attacker access to the playbook run.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly enforce channel member management permissions in playbook runs, allowing authenticated users without the 'Manage Channel Members' permission to add or remove users from public and private channels by manipulating playbook run participants when the run is linked to a channel.
A remote code execution vulnerability (CVSS 9.9) that allows authenticated users. Critical severity with potential for significant impact on affected systems.
Mattermost versions 10.7.x <= 10.7.1, 10.6.x <= 10.6.3, 10.5.x <= 10.5.4, 9.11.x <= 9.11.13 fail to properly validate LDAP group ID attributes, allowing an authenticated administrator with PermissionSysconsoleWriteUserManagementGroups permission to execute LDAP search filter injection via the PUT /api/v4/ldap/groups/{remote_id}/link API when objectGUID is configured as the Group ID Attribute.
Mattermost versions 10.5.x <= 10.5.4, 9.11.x <= 9.11.13 fail to properly restrict API access to team information, allowing guest users to bypass permissions and view information about public teams they are not members of via a direct API call to /api/v4/teams/{team_id}.
Mattermost versions 10.7.x <= 10.7.0, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fails to properly enforce access control restrictions for System Manager roles, allowing authenticated users with System. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fails to properly invalidate personal access tokens upon user deactivation, allowing deactivated users to. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to clear Google OAuth credentials when converting user accounts to bot accounts, allowing attackers to. Rated medium severity (CVSS 4.2), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to properly enforce access controls for guest users accessing channel member information, allowing authenticated guest. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to properly validate permissions when changing team privacy settings, allowing team administrators. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.3, 9.11.x <= 9.11.11 fail to check `RestrictSystemAdmin` setting if user doesn't have access to `ExperimentalSettings` which allows a System Manager to access. Rated low severity (CVSS 2.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.2, 9.11.x <= 9.11.11 failed to properly verify a user's permissions when accessing groups, which allows an attacker to view group information via an API request. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.6.x <= 10.6.1, 10.5.x <= 10.5.2, 10.4.x <= 10.4.4, 9.11.x <= 9.11.11 fail to check the correct permissions which allows authenticated users who only have permission to invite. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.6.x <= 10.6.1, 10.5.x <= 10.5.2, 10.4.x <= 10.4.4, 9.11.x <= 9.11.11 fail to lockout LDAP users following repeated login failures, which allows attackers to lock external LDAP. Rated medium severity (CVSS 5.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Incorrect authorization in Mattermost's Boards component across versions 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 enables privilege escalation within board management. Board editors and non-guest team members can supply arbitrary values in BoardMember.Scheme* fields through the boards member API or archive-import endpoint, effectively granting board admin rights to any user without server-side enforcement. No public exploit has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Authenticated Mattermost users can degrade message post-processing latency for every member of the channels they share by storing an oversized list of custom mention keywords (notify_props.mention_keys) on their own profile, which the server then matches against each post. Because the matching routine scales quadratically and multibyte/Unicode keywords add per-character cost, and neither the number nor the size of stored keywords is capped, each post the attacker's channel peers send or receive is processed far more expensively on the attacker's behalf. Impact is confined to availability degradation (CVSS 4.3, AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L; CWE-770); no data exposure or crash is involved, valid authentication plus at least one shared channel is required, and no public exploit has been identified at time of analysis.
Information disclosure in Mattermost release lines 11.7.x, 11.8.x, 11.9.x and 11.10.x (up to 11.7.10, 11.8.5, 11.9.1 and 11.10.1 respectively) allows an authenticated user to learn the channel ID of a private channel that another user is actively viewing. The user status API endpoints return an unsanitized active-channel field, so any provisioned account on the same server - with no membership in the target private channel, which is precisely the flaw - can query another user's status and observe which private channel that user is currently reading. The exposure is limited to the channel identifier itself, not its contents, name or membership, but it still reveals the existence of private channels and correlates named users with sensitive collaboration spaces. Rated CVSS 4.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N), this is a low-to-moderate urgency issue rather than an emergency, and no public exploit has been identified at time of analysis.
Mattermost 11.7.x through 11.10.x fails to invalidate the stored AD/LDAP bind password whenever other connection settings - such as the directory server address - are changed in the System Console, so the previously saved plaintext credential is carried over to the new configuration. An authenticated System Console administrator (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N, base 4.9) can then trigger the LDAP Test Connection / diagnostics feature, which transmits that retained plaintext bind password to the configured server address, potentially an attacker-controlled host set by the same admin. There is confirmed no CISA KEV entry and no public exploit identified at time of analysis, and no EPSS score was supplied; exploitation is gated behind high-privilege System Console access, an existing AD/LDAP integration with a stored bind password, and the deliberate admin action of pointing the connection at a hostile host, making this a genuine but moderate-priority confidentiality issue rather than an emergency.
Mattermost Server versions 11.7.x through 11.10.x can disclose the stored client secret of an outgoing OAuth connection to an attacker who holds the administrative permission to manage those connections. The platform fails to require re-entry of the stored secret during connection validation, so an authenticated high-privileged user can repoint the connection's token URL at an attacker-controlled endpoint and trigger validation, causing the secret to be sent to that endpoint (CWE-201, information disclosure). Our assessment rates this CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N), with the practical risk tempered by the privilege prerequisite - the feature must be enabled and at least one outgoing OAuth connection with a stored secret must already exist; no public exploit was identified at time of analysis and there is no KEV listing. Exploitation is remote, requires no victim interaction, and yields confidentiality impact only (no integrity or availability impact).
Authenticated users on Mattermost Server 11.7.x through 11.10.0 can quarantine posts inside direct and group messages they are not participants of by issuing a direct API call to the post-quarantine endpoint, because the server performs no DM/GM membership or authorization check before processing the request (CWE-862, Missing Authorization). The flaw is remotely reachable over the network but requires a valid low-privileged account (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L per the assessed vector), and the realistic impact is improper manipulation of the moderation/quarantine state of DM and GM posts rather than disclosure of message contents or full data compromise. There is no public exploit identified at time of analysis and no confirmed active exploitation (no CISA KEV entry); this is a moderate-severity authorization weakness that Mattermost tracks under advisory MMSA-2026-00756.
Authenticated guest accounts on Mattermost 11.7.x through 11.7.9, 11.8.x through 11.8.5, 11.9.x through 11.9.1, and 11.10.0 can be escalated to team or channel administrator by abusing the member roles API endpoint, which fails to validate a crafted combination of guest and admin scheme roles. The flaw requires only a valid guest login and network reachability to the API, so any server that provisions guest accounts is exposed, though no public exploit code or confirmed active exploitation has been identified at time of analysis. Vendor advisory MMSA-2026-00752 tracks the issue, and Mattermost has published it on its security updates page.
Mattermost's data retention teams API endpoint fails to sanitize returned Team objects, exposing private teams' secret `invite_id` and email fields to any authenticated user holding only the read-only Data Retention Policy permission. An attacker exploiting CVE-2026-91181 can call `GET /api/v4/data_retention/policies/{policy_id}/teams`, harvest the `invite_id` of private teams they have no membership in, and use it to join those teams without authorization - effectively achieving lateral movement across private channels and communications. No public exploit code has been identified and the vulnerability is not listed in CISA KEV at time of analysis.
Incorrect authorization in Mattermost Boards allows an authenticated board editor to relink any editable board to an arbitrary channel by exploiting a missing PermissionManageBoardRoles check on the channelId field of the batch endpoint. Affected are Mattermost versions 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 (advisory MMSA-2026-00686). No public exploit code or CISA KEV listing has been identified at time of analysis, but the low attack complexity and network accessibility make this straightforward to execute for any authenticated board editor.
Denial of service in Mattermost's Boards (focalboard) plugin allows any authenticated user to crash the plugin process and disrupt Boards availability for all users on the instance by sending a single malformed WebSocket message. The root cause is absent input validation on the teamId field type in custom_focalboard_SUBSCRIBE_TEAM WebSocket commands, classified under CWE-704 (Incorrect Type Conversion). Affected versions span 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3; no public exploit has been identified at time of analysis.
Privilege escalation in Mattermost's channel administration API allows authenticated channel administrators to assign non-channel-scoped roles to channel members, exceeding their intended authorization boundary. Three active release lines are affected: 10.11.x through 10.11.21, 11.7.x through 11.7.6, and 11.8.x through 11.8.2. No public exploit code has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Private channel membership disclosure in Mattermost's Boards feature allows any authenticated team member to enumerate who belongs to private channels they are not authorized to view. Affected across three concurrently maintained release trains - 11.7.x through 11.7.6, 10.11.x through 10.11.21, and 11.8.x through 11.8.3 - the flaw is exploitable by any valid team account via standard board management API calls. No public exploit or active exploitation has been identified at time of analysis; the CVSS score of 4.3 (PR:L, C:L) accurately reflects the limited but real confidentiality impact, particularly meaningful in regulated environments where private channel membership itself is sensitive.
Mattermost's Playbooks feature in versions 11.7.x through 11.7.6 and 10.11.x through 10.11.21 omits run-state enforcement on API write operations, allowing any authenticated run participant to alter completed playbook runs via REST and GraphQL endpoints. An attacker with low privileges can overwrite status, checklists, retrospective content, ownership, and participant lists on runs that should be immutable once finished, undermining post-incident audit integrity. No public exploit has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Incorrect authorization in Mattermost's OAuth and personal access token management endpoints allows an OAuth application holding a delegated user token to call account-management endpoints beyond its intended scope, revoking the victim user's authorizations or tokens for unrelated integrations. Affected are Mattermost 11.7.0 through 11.7.6 and 10.11.0 through 10.11.21. No public exploit code has been identified and this vulnerability is not listed in the CISA KEV catalog, though the low-complexity, network-accessible nature of the flaw makes it straightforward to abuse for any actor who has legitimately obtained an OAuth delegated token.
Privilege escalation in Mattermost's Boards feature allows a low-privileged board member to elevate a guest user to Board Admin by importing a specially crafted .boardarchive file. Affected are Mattermost versions 10.11.0 through 10.11.21 and 11.7.0 through 11.7.6. No public exploit or KEV listing has been identified, but the low attack complexity and the insider-threat profile make this a meaningful risk in multi-tenant or externally-collaborative Mattermost deployments.
Incorrect authorization in Mattermost's ABAC policy unassign API endpoint allows an authenticated team administrator to remove attribute-based access control policy assignments from channels that no longer belong to their team. Affected releases are Mattermost 11.7.0 through 11.7.6 and 11.8.0 through 11.8.3, tracked as MMSA-2026-00718 (ENISA EUVD-2026-60212). The exploit window opens when a channel is migrated between teams and the endpoint fails to re-verify team membership before executing the unassignment, letting a malicious admin modify access-control policy state beyond their administrative boundary.
Privilege retention in Mattermost Boards allows a user demoted to System Guest to continue exercising Board Admin privileges via the Boards REST API or UI. Affected are Mattermost versions 11.7.0-11.7.6, 10.11.0-10.11.21, and 11.8.0-11.8.3, where the SchemeAdmin flag is not reconciled against the user's current role during or after demotion. An authenticated attacker in this state can invoke admin-only Boards operations - including modifying board permissions and settings - without detection by role-based access checks. No public exploit code is identified and no CISA KEV listing is present at time of analysis.
Server-side request forgery in the Mattermost Agents plugin MCP server (stdio mode) allows a low-privileged local attacker to make the server fetch arbitrary internal URLs submitted as file attachment references in post creation requests, enabling exfiltration of data from RFC 1918-addressed services on the internal network. Affected are Mattermost deployments running versions 10.11.x ≤ 10.11.18, 11.5.x ≤ 11.5.6, and 11.6.x ≤ 11.6.3 with the Agents plugin's MCP server active in stdio mode. No public exploit code or CISA KEV listing is present in the available data; exploitation is constrained to attackers who already have local access to the stdio MCP interface.
Markdown image rendering restrictions in Mattermost are bypassed specifically for AI bot tool result posts, enabling authenticated attackers to exfiltrate data to attacker-controlled infrastructure. Affected are Mattermost versions 10.11.x through 10.11.18, 11.5.x through 11.5.6, and 11.6.x through 11.6.3. When a victim's client renders an AI bot tool result post containing injected markdown image syntax, the client issues an outbound request to the attacker's server, leaking request metadata such as session tokens or channel context. No public exploit code exists and this vulnerability is not listed in the CISA KEV catalog at time of analysis.
Mattermost Server versions 11.3.0, 11.2.x through 11.2.2, and 10.11.x through 10.11.10 contain a server-side request forgery (SSRF) vulnerability due to improper validation of IPv4-mapped IPv6 addresses, allowing authenticated attackers to bypass reserved IP restrictions and access internal services. An attacker with login credentials can craft requests using IPv6 notation (such as [::ffff:127.0.0.1]) to reach localhost or other restricted internal endpoints that would normally be blocked. No patch is currently available for this vulnerability.
A remote code execution vulnerability (CVSS 4.3) that allows guest users without read permissions. Remediation should follow standard vulnerability management procedures.
CVE-2026-22545 is a security vulnerability (CVSS 3.1) that allows an authenticated attacker. Remediation should follow standard vulnerability management procedures.
CVE-2026-21386 is a security vulnerability (CVSS 4.3) that allows an authenticated team member. Remediation should follow standard vulnerability management procedures.
Mattermost versions 10.11.x <= 10.11.9 fail to enforce invite permissions when updating team settings, which allows team administrators without proper permissions to bypass restrictions and add users to their team via API requests. Mattermost Advisory ID: MMSA-2025-00561 [CVSS 3.8 LOW]
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate team membership when processing channel mentions which allows authenticated users to determine the existence of teams and their URL names via posting channel shortlinks and observing the channel_mentions property in the API response. [CVSS 4.3 MEDIUM]
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. [CVSS 5.7 MEDIUM]
Mattermost Server versions 11.1.x through 11.1.2, 10.11.x through 10.11.9, and 11.2.x through 11.2.1 inadequately enforce login method restrictions, permitting authenticated users to circumvent SSO-only requirements by authenticating with a userID instead. This allows an attacker with valid credentials to gain unauthorized access to accounts restricted to single sign-on authentication. No patch is currently available for this vulnerability.
Insufficient identity validation in Mattermost Server (versions 11.1.x through 11.2.1 and earlier) and Zoom Plugin (versions up to 1.11.0) allows authenticated users to initiate Zoom meetings as arbitrary users and modify other users' posts through direct API manipulation. An attacker with valid credentials can exploit the /api/v1/askPMI endpoint to impersonate other users and alter post content without proper authorization checks. The vulnerability affects multiple Mattermost and plugin versions with no patch currently available.
Mattermost and Zoom plugin versions fail to properly authenticate users before allowing modifications to Zoom meeting restrictions, enabling any logged-in user to alter meeting settings across arbitrary channels. Affected versions include Mattermost 11.1.x through 11.1.2, 10.11.x through 10.11.9, 11.2.x through 11.2.1, and Zoom plugin versions up to 1.11.0. No patch is currently available for this privilege escalation vulnerability.
Mattermost versions 11.1.2, 10.11.9, and 11.2.1 and earlier fail to properly enforce access controls in the Jira plugin's /create-issue API endpoint, allowing authenticated users to read restricted post content and attachments from channels they cannot access by referencing post IDs. An attacker with Jira plugin access can exploit this to enumerate and exfiltrate sensitive information from private or restricted channels. No patch is currently available for affected versions.
Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549 [CVSS 3.1 LOW]
Mattermost versions 10.11.x <= 10.11.8, 11.1.x <= 11.1.1, 11.0.x <= 11.0.6 fail to prevent infinite re-renders on API errors which allows authenticated users to cause application-level DoS via triggering unbounded component re-render loops. [CVSS 6.8 MEDIUM]
Mattermost versions 10.11.x <= 10.11.8 fail to validate input size before processing hashtags which allows an authenticated attacker to exhaust CPU resources via a single HTTP request containing a post with thousands space-separated tokens [CVSS 3.1 LOW]
Incorrect authorization in Mattermost Server lets any authenticated user forge a '/share-issue-publicly' post action, so that when a victim user interacts with the crafted post, Jira ticket content the victim is authorized to see is relayed to the attacker. Affected lines are 10.11.x through 10.11.7, 10.12.x through 10.12.3, 11.0.x through 11.0.5, and 11.1.x through 11.1.0, and exploitation requires the Jira plugin to be installed, an account able to post into a channel the victim reads, and victim interaction (CVSS 3.1 4.1, AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N). No public exploit code and no confirmed active exploitation were identified at time of analysis, and the exposure is limited to Jira ticket data rather than server compromise.
Mattermost Server versions 10.11.x through 11.1.0 contain an authorization bypass in the Jira plugin's post-to-comment feature that lets an authenticated user read posts and attachments from channels they are not allowed to access. Exploitation requires a valid Mattermost account and an enabled/configured Jira integration where posts can be attached as Jira comments, with impact limited to confidentiality of exposed post content; no public exploit identified at time of analysis. The CVSS 3.1 score of 4.3 reflects a moderate issue rather than a high-severity breach.
Improper authentication enforcement in the Mattermost Jira plugin lets an unauthenticated attacker who knows a valid Mattermost user ID send crafted plugin payloads that spoof that user and inject arbitrary Jira issue-key paths, causing the plugin to issue authenticated GET and POST requests to the connected Jira server. The flaw affects Mattermost Server 11.1.x through 11.1.0, 11.0.x through 11.0.5, 10.12.x through 10.12.3, and 10.11.x through 10.11.7, but only when the Jira plugin (versions <= 4.4.0) is installed, enabled, and connected to Jira; default installations without the Jira integration are not exposed. Per the CVSS vector the attack is unauthenticated and needs no user interaction, and the decisive practical barrier is that the attacker must possess or guess a usable Mattermost user ID. No confirmed active exploitation has been reported (not in CISA KEV) and no public exploit code has been identified; EPSS is low at 0.26% (17th percentile), so this is a mid-tier priority rather than an emergency. Mattermost Advisory ID: MMSA-2025-00555.
Mattermost Server versions 10.11.x through 10.12.2 fail to invalidate remote cluster invite tokens when using the legacy (v1) protocol or when the confirming party omits a refreshed token, allowing an attacker who has obtained a valid invite token to authenticate as the remote cluster and perform limited actions on shared channels. The vulnerability is rated low severity (CVSS 3.7) with an EPSS of 0.20%, and no public exploit or active exploitation has been reported.
Denial of service in Mattermost Server affects versions 11.0.x through 11.0.4, 10.12.x through 10.12.2, and 10.11.x through 10.11.6 when the Calls plug-in is enabled: a malformed WebSocket request field that is not valid UTF-8 is not rejected, causing the Calls plug-in to crash. The attacker must be an authenticated, low-privilege user (CVSS vector PR:L) capable of opening a WebSocket connection to the server, and the impact is limited to availability of the calling functionality with no data exposure or code execution. Severity is medium (CVSS 6.5, C:N/I:N/A:H); EPSS is 0.29% (20th percentile) and no public exploit identified at time of analysis - this is a medium-severity availability issue, not a top-tier priority.
Open redirect in Mattermost Server 10.11.x through 10.11.4 (CVE-2025-62690) allows unauthenticated remote attackers to redirect victims to arbitrary external sites by crafting a link to the /error endpoint that fails to validate the redirect URL. The attack requires the victim to open the link in a new tab (user interaction), and it enables phishing or credential harvesting rather than server compromise. No public exploit code or active exploitation has been identified, and the EPSS score is 0.15% (4th percentile), indicating low likelihood of exploitation.
Cross-site request forgery in the Mattermost Calls widget page allows an attacker to initiate calls and inject messages into channels or direct messages as a logged-in victim who is lured to a malicious webpage or crafted link. Affected deployments are Mattermost Server 11.0.x through 11.0.4, 10.12.x through 10.12.2, and 10.11.x through 10.11.6, plus Mattermost Calls plugin versions 1.10.0 and earlier; instances not running the Calls feature are not exposed. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N, score 4.3) confirms the attack is network-reachable with no attacker-side privileges but requires victim interaction, and impact is limited to low-integrity actions with no confidentiality or availability loss. No public exploit identified at time of analysis, and EPSS is 0.12% (2nd percentile), indicating low predicted exploitation activity; the flaw is a genuine but low-urgency medium-severity issue.
Reaction forwarding in the Mattermost GitHub plugin (versions <= 2.4.0) running on Mattermost Server 10.11.x (<= 10.11.6) fails to validate the plugin bot identity, letting an authenticated low-privilege user post crafted notification messages that cause another user to add reactions to arbitrary GitHub objects. The impact is limited to integrity (spoofed reactions on third-party GitHub content) with no confidentiality or availability loss, and exploitation requires high attack complexity plus victim interaction. EPSS is 0.18% (6th percentile), there is no CISA KEV entry, and no public exploit code was identified at time of analysis, so this is a low-priority, non-actively-exploited issue.
Access-control weakness in Mattermost Server 10.5.x through 10.5.12 and 10.11.x through 10.11.4 allows an authenticated user to retrieve files from Boards they are not a member of and to subscribe to blocks on inaccessible boards when they know the relevant identifiers. The issue is confidentiality-only (CVSS 4.3, C:L) and requires a valid account (PR:L), so it is not an anonymous authentication bypass despite the 'Authentication Bypass' tag. No public exploit identified at time of analysis and EPSS is very low (0.04%, 12th percentile); vendor patch is available.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to validate user permissions when deleting comments in Boards, which allows an authenticated user with the editor role to delete comments created by other users.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to sanitize team email addresses to be visible only to Team Admins, which allows any authenticated. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to enforce access permissions on the Agents plugin which allows other users to determine when users had read channels via channel member. Rated low severity (CVSS 3.0), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to sanitize user data which allows system administrators to access password hashes and MFA secrets via the POST. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost Server releases before version 11 do not enforce multi-factor authentication on the WebSocket connection path, so an unauthenticated remote attacker who can reach the server's WebSocket endpoint can receive sensitive information carried in WebSocket events even when the deployment relies on MFA for its HTTP login flow. Because the flaw is a missing-auth-check on a separate protocol channel rather than a credential compromise, no privileges or user interaction are required (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), but impact is limited to confidentiality - no modification or disruption. EPSS is low at 0.15% (36th percentile) and no public exploit code or CISA KEV entry was identified at time of analysis, so this is a genuine but moderate-priority issue rather than a top-tier emergency; exposure is concentrated on internet-reachable instances that actually use MFA, and is moot on deployments that do not rely on MFA.
Mattermost versions <11.0 fail to properly enforce the "Allow users to view archived channels" setting which allows regular users to access archived channel content and files via the "Open in. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost Server 10.11.x through 10.11.1, 10.10.x through 10.10.2, and 10.5.x through 10.5.10 allows an authenticated low-privileged user to join any team despite join restrictions by manipulating the RelayState value in the invite-token flow. The root cause is a missing authorization check (CWE-862) that fails to verify the user's permission to join the team associated with the original invite token. No public exploit identified at time of analysis, but the CVSS 8.1 rating reflects high confidentiality and integrity impact from unauthorized team access; exploitation requires a valid account on the target server.
Mattermost Server 10.11.x through 10.11.1, 10.10.x through 10.10.2, and 10.5.x through 10.5.10 contains a missing authorization flaw that allows an authenticated user to bypass team-join restrictions by manipulating the OAuth state parameter so the server reuses the original invite token without rechecking permissions. This lets an attacker with a valid account join teams they should not access, with high confidentiality and integrity impact but no availability impact. No public exploit identified at time of analysis; exploitation depends on a valid account and an OAuth-based join flow that carries the invite token in state.
Mattermost Server 10.5.x through 10.5.10 and 10.11.x through 10.11.2 uses non-constant-time comparisons when validating Cloud API keys and OAuth client secrets, creating a timing side channel that could theoretically let remote, unauthenticated attackers recover those secrets byte by byte through repeated response-time measurements. The high attack complexity reflects the need for precise, high-volume timing measurements against stable low-latency endpoints without rate limiting or timing noise; only those two secret-validation paths are affected, and no public exploit code or confirmed active exploitation was identified at time of analysis. EPSS is low at 0.27 percent (18th percentile), consistent with a low-priority information disclosure issue.
Mattermost Server 10.5.x through 10.5.10, 10.10.x through 10.10.2, and 10.11.x through 10.11.2 does not validate email ownership during the Slack import workflow, allowing an attacker who can supply import data to create verified accounts under arbitrary email domains and bypass email-domain-based team access restrictions. The flaw is a missing-authorization issue (CWE-862) rated CVSS 5.4 with a PR:L vector, though Slack import is generally a team or system admin function, so the practical privilege barrier may be higher than PR:L suggests. No public exploit code or CISA KEV entry is identified at time of analysis, and EPSS is low at 0.30% (22nd percentile).
Guest users on Mattermost Server 10.5.x through 10.5.10 and 10.11.x through 10.11.2 can bypass channel-membership authorization by calling the /api/v4/channels/{channel_id}/members endpoint, adding arbitrary team members to private channels they belong to. The flaw is an incorrect authorization check (CWE-863) scored CVSS 4.3 as an authenticated, network-reachable issue with low confidentiality impact and no integrity or availability effect. Exploitation requires a provisioned guest account and the guest feature in use, limiting realistic exposure to insiders or compromised guest credentials; EPSS is 0.33% (24th percentile), no public exploit code or CISA KEV entry was identified at time of analysis, and Mattermost has published patched releases.
Information disclosure in Mattermost Server 10.5.x through 10.5.12 and 10.11.x through 10.11.2 allows authenticated guest users to enumerate active public channels and their metadata via the /api/v4/teams/{team_id}/channels/ids endpoint. The issue is a missing-authorization condition in guest permission checks; exploitation requires a valid guest account, guest access enabled, and membership in the relevant team, and is limited to public-channel identifiers and metadata with no message content, write access, or availability impact. No public exploit code was identified at time of analysis, and EPSS is low at 0.31% (22nd percentile), making this a low-to-moderate severity information-disclosure issue rather than an emergency.
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate access controls which allows any authenticated user to download sensitive files via board file download endpoint. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost Server versions 10.8.x through 10.8.3, 10.5.x through 10.5.8, 9.11.x through 9.11.17, 10.10.x through 10.10.1, and 10.9.x through 10.9.3 contain a path-traversal weakness that lets an authenticated system administrator achieve remote code execution by configuring an unvalidated import directory path and uploading a malicious plugin to the prepackaged plugins directory. The attacker must already hold the high-privilege admin role, so the practical risk is concentrated in malicious insiders, compromised admin sessions, or post-exploitation chains rather than unauthenticated external attacks. At time of analysis, no public exploit identified at time of analysis, and EPSS is low at 0.03% (10th percentile); patch availability is confirmed per vendor advisory.
Mattermost versions 10.5.x <= 10.5.9 fail to properly validate redirect URLs which allows attackers to redirect users to malicious sites via crafted OAuth login URLs. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
Mattermost versions 10.10.x <= 10.10.1, 10.5.x <= 10.5.9, 10.9.x <= 10.9.4 fail to validate the redirect_to parameter, allowing an attacker to craft a malicious link that, once a user authenticates. Rated high severity (CVSS 7.6), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to properly validate cache keys for link metadata which allows authenticated users. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to sanitize file names which allows users with file upload permission to overwrite file attachment. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Members to Guests via the. Rated low severity (CVSS 3.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.8 fail to validate access controls at time of access which allows user to read a thread via AI posts. Rated low severity (CVSS 3.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2, 10.10.x <= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fail to sanitize the team invite ID in the POST /api/v4/teams/:teamId/restore endpoint which allows an team. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost Server versions 10.5.x <= 10.5.9 utilizing the Agents plugin fail to reject empty request bodies which allows users to trick users into clicking malicious links via post actions. Rated low severity (CVSS 3.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive information about linked private channels including channel name, display name, and participant count through the run metadata API endpoint.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly enforce channel member management permissions when adding participants to playbook runs. This allows authenticated users with member-level permissions to bypass system admin restrictions and add or remove users to/from private channels via the playbook run participants feature, even when the 'Manage Members' permission has been explicitly removed. This can lead to unauthorized access to sensitive channel content and allow guest users to gain channel management privileges.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly retrieve requestorInfo from playbooks handler for guest users which allows an attacker access to the playbook run.
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly enforce channel member management permissions in playbook runs, allowing authenticated users without the 'Manage Channel Members' permission to add or remove users from public and private channels by manipulating playbook run participants when the run is linked to a channel.
A remote code execution vulnerability (CVSS 9.9) that allows authenticated users. Critical severity with potential for significant impact on affected systems.
Mattermost versions 10.7.x <= 10.7.1, 10.6.x <= 10.6.3, 10.5.x <= 10.5.4, 9.11.x <= 9.11.13 fail to properly validate LDAP group ID attributes, allowing an authenticated administrator with PermissionSysconsoleWriteUserManagementGroups permission to execute LDAP search filter injection via the PUT /api/v4/ldap/groups/{remote_id}/link API when objectGUID is configured as the Group ID Attribute.
Mattermost versions 10.5.x <= 10.5.4, 9.11.x <= 9.11.13 fail to properly restrict API access to team information, allowing guest users to bypass permissions and view information about public teams they are not members of via a direct API call to /api/v4/teams/{team_id}.
Mattermost versions 10.7.x <= 10.7.0, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fails to properly enforce access control restrictions for System Manager roles, allowing authenticated users with System. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fails to properly invalidate personal access tokens upon user deactivation, allowing deactivated users to. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to clear Google OAuth credentials when converting user accounts to bot accounts, allowing attackers to. Rated medium severity (CVSS 4.2), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to properly enforce access controls for guest users accessing channel member information, allowing authenticated guest. Rated low severity (CVSS 3.1), this vulnerability is remotely exploitable. No vendor patch available.
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to properly validate permissions when changing team privacy settings, allowing team administrators. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.3, 9.11.x <= 9.11.11 fail to check `RestrictSystemAdmin` setting if user doesn't have access to `ExperimentalSettings` which allows a System Manager to access. Rated low severity (CVSS 2.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.5.x <= 10.5.2, 9.11.x <= 9.11.11 failed to properly verify a user's permissions when accessing groups, which allows an attacker to view group information via an API request. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.6.x <= 10.6.1, 10.5.x <= 10.5.2, 10.4.x <= 10.4.4, 9.11.x <= 9.11.11 fail to check the correct permissions which allows authenticated users who only have permission to invite. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Mattermost versions 10.6.x <= 10.6.1, 10.5.x <= 10.5.2, 10.4.x <= 10.4.4, 9.11.x <= 9.11.11 fail to lockout LDAP users following repeated login failures, which allows attackers to lock external LDAP. Rated medium severity (CVSS 5.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.