High severity · published Oct 28, 2026
CVE-2026-93851
Path traversal in Mattermost Agents plugin mention reminder allows plugin replacement via crafted post
New
8.0
CVSS
–
EPSS
No
On KEV
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
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
11.9.0 through 11.9.1; 11.8.0 through 11.8.5; 11.7.0 through 11.7.10 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-93851
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-93851
vendor-advisory
https://mattermost.com/security-updates
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