What is the CVSS score of EUVD-2026-30760?

EUVD-2026-30760 has a CVSS 3.1 base score of 4.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N. EPSS exploitation probability: 0.0%.

Is there a patch available for EUVD-2026-30760?

Yes, a patch is available for EUVD-2026-30760. Update the affected software to the latest version immediately.

Mattermost EUVD-2026-30760

Q: Which versions of Mattermost are affected by EUVD-2026-30760?

Authenticated team members with 'Manage Own Slash Commands' permission can hijack existing slash commands in Mattermost 11.5.x through 11.5.1, 10.11.x through 10.11.13, and 11.4.x through 11.4.3 by…. A patch is available.

| CVE-2026-28732 MEDIUM

Incorrect Authorization (CWE-863)

2026-05-18 Mattermost

GHSA-wvcv-9xpm-7mqc

Mattermost Authentication Bypass

4.3

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

4.3 MEDIUM

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

May 18, 2026 - 09:32 vuln.today

DescriptionCVE.org

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597

AnalysisAI

Authenticated team members with 'Manage Own Slash Commands' permission can hijack existing slash commands in Mattermost 11.5.x through 11.5.1, 10.11.x through 10.11.13, and 11.4.x through 11.4.3 by editing their own command triggers to match already-registered system or custom commands. This privilege escalation flaw (CWE-863: Incorrect Authorization) enables command impersonation, allowing attackers to intercept and potentially manipulate user interactions with legitimate slash commands. With CVSS 4.3 (low-medium severity) and EPSS data unavailable, real-world risk depends heavily on organizational use of slash commands for sensitive operations. No public exploit identified at time of analysis, and the attack requires authenticated access with specific permissions, limiting immediate exposure compared to unauthenticated network vulnerabilities.

Technical ContextAI

Mattermost is an open-source team collaboration platform supporting custom integrations via slash commands - user-triggered actions prefixed with forward slashes (e.g., '/remind', '/deploy'). The command update API (used when users modify their own slash commands) fails to validate trigger-word uniqueness against the global command registry. This violates authorization logic (CWE-863: Incorrect Authorization) by allowing users with 'Manage Own Slash Commands' permission to overwrite trigger words belonging to system-level or other users' commands. The vulnerability exists in the command update code path specifically - initial command creation may properly enforce uniqueness, but subsequent edits bypass this check. Affected CPE 2.3:a:mattermost:mattermost:*:*:*:*:*:* spans three concurrent release branches (10.11.x, 11.4.x, 11.5.x), suggesting the flaw was introduced in shared upstream code predating the 10.11 series and persisted through multiple major versions.

RemediationAI

Upgrade to patched Mattermost versions released after 11.5.1, 10.11.13, and 11.4.3 respectively for each affected branch - consult Mattermost Security Advisory MMSA-2026-00597 at https://mattermost.com/security-updates for exact fixed version numbers, which were not provided in NVD data at time of analysis. Organizations unable to immediately patch should implement compensating controls: (1) Audit and restrict the 'Manage Own Slash Commands' permission to only highly trusted users via System Console > User Management > Permissions, accepting trade-off of reduced self-service command management; (2) Monitor command modification events via audit logs (if available in your Mattermost edition) to detect suspicious trigger-word changes matching existing system commands; (3) Document all critical system slash command triggers and periodically verify they remain owned by authorized service accounts, not regular users - this manual verification adds operational overhead but detects hijacking attempts post-exploitation. For high-risk environments using commands for privileged operations, consider temporarily disabling custom slash command creation/editing until patching completes, though this breaks legitimate workflows. Administrative review of existing slash commands for duplicate triggers should be performed immediately to identify already-compromised commands.