Is CVE-2026-93851 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-93851?

CVE-2026-93851 has a CVSS v3 severity of HIGH (8).

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CVE-2026-93851

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