What is the CVSS score of CVE-2026-6957?

CVE-2026-6957 has a CVSS 3.1 base score of 8.0 (High). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Mattermost Plugins are affected by CVE-2026-6957?

Mattermost Plugins versions 1.1.5 and earlier are vulnerable to arbitrary file writes when federated with untrusted server instances, potentially allowing compromised federated partners to inject…

Mattermost Plugins CVE-2026-6957

Q: How to fix or mitigate CVE-2026-6957?

Within 24 hours: identify all Mattermost servers running Plugins version 1.1.5 or earlier; audit current federation relationships and disable connections to untrusted peers; restrict administrative account usage to essential personnel. Within 7 days: implement network segmentation to isolate federated Mattermost connections from critical infrastructure; deploy file integrity monitoring on affected servers; audit administrative activities on federated instances over the past 90 days. Within 30 days: monitor vendor security advisories for patch availability; prepare upgrade procedures for rapid deployment when patches are released; conduct comprehensive security assessment of Mattermost federation configuration.

EUVD-2026-32523 HIGH

Path Traversal (CWE-22)

2026-05-27 responsibledisclosure@mattermost.com

GHSA-x7w4-j7hv-94wg

Path Traversal Mattermost

8.0

CVSS 3.1

CVSS VectorNVD

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

May 27, 2026 - 20:08 vuln.today

DescriptionNVD

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

AnalysisAI

Arbitrary file write in Mattermost Plugins (versions ≤1.1.5) lets an administrator of a remote, federated Mattermost server plant files at attacker-chosen paths inside the target server's filestore by supplying a malicious, unsanitized filename through the shared-channel attachment sync protocol. The flaw stems from CWE-22 path traversal in the export-path construction logic and carries CVSS 8.0 with a changed scope, reflecting that a compromised or hostile federation peer can affect resources beyond the plugin's intended boundary. …

RemediationAI

Within 24 hours: identify all Mattermost servers running Plugins version 1.1.5 or earlier; audit current federation relationships and disable connections to untrusted peers; restrict administrative account usage to essential personnel. Within 7 days: implement network segmentation to isolate federated Mattermost connections from critical infrastructure; deploy file integrity monitoring on affected servers; audit administrative activities on federated instances over the past 90 days. …

Analysis

Detailed AI-generated intelligence summary covering attack vector, impact assessment, affected versions, remediation steps, and indicators of compromise.

POChttps://••••••••••.com/exploit

PATCHhttps://••••••••••.com/patch

ADVISORYhttps://••••••••••.com/advisory

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CVE-2026-6957 vulnerability details – vuln.today

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Mattermost Plugins CVE-2026-6957

CVSS VectorNVD

Lifecycle Timeline

DescriptionNVD

AnalysisAI

RemediationAI

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External POC / Exploit Code