CVE-2026-93851

Path traversal in Mattermost Agents plugin mention reminder allows plugin replacement via crafted post

Published Oct 28, 2026 CVSS 3.1 · 8 High EPSS < 1% KEV · Not listed
Description
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to cause the administrator's browser to send an unintended API request, resulting in replacement of an installed plugin and code execution on the server, via a crafted post containing a forged mention reminder that the administrator clicks. Mattermost Advisory ID: MMSA-2026-00742

Remediation

Vendor Solution

Update Mattermost to versions 11.10.0, 11.9.2, 11.8.6, 11.7.11 or higher.

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Description Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to cause the administrator's browser to send an unintended API request, resulting in replacement of an installed plugin and code execution on the server, via a crafted post containing a forged mention reminder that the administrator clicks. Mattermost Advisory ID: MMSA-2026-00742
Title Path traversal in Mattermost Agents plugin mention reminder allows plugin replacement via crafted post
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Oct 30, 2026, 3:56 AM
Reserved
Sep 18, 2026, 6:43 PM
Status
Awaiting Analysis
Published
Oct 28, 2026, 10:17 PM
Modified
Oct 30, 2026, 4:18 AM