8.0
High
CVE-2026-93851 Mattermost versions…
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
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Mattermost 11.10 | earliest → < 11.10.0 | 11.10.0 |
| Mattermost 11.9 | 11.9.0 → 11.9.1 | 11.9.2 |
| Mattermost 11.8 | 11.8.0 → 11.8.5 | 11.8.6 |
| Mattermost 11.7 | 11.7.0 → 11.7.10 | 11.7.11 |