CVE-2026-93851

EUVD-2026-112505

28.10.2026, 22:17

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

Path Traversal

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
Mattermost	CNA	8 HIGH	NETWORK	HIGH	LOW	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).

Vendor	Product	Version	Source
mattermost	mattermost	11.9.0 ≤ 𝑥 ≤ 11.9.1	CNA
mattermost	mattermost	11.8.0 ≤ 𝑥 ≤ 11.8.5	CNA
mattermost	mattermost	11.7.0 ≤ 𝑥 ≤ 11.7.10	CNA

Common Weakness Enumeration

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

References

https://mattermost.com/security-updates