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HIGH · 8.0

CVE-2026-93851

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 ...

Vulnerability 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 Score

8.0

HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Related Weaknesses (CWE)

CWE-22

References

FAQ

What is CVE-2026-93851?

CVE-2026-93851 is a vulnerability with a CVSS score of 8.0 (HIGH). 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 ...

How severe is CVE-2026-93851?

CVE-2026-93851 has been rated HIGH with a CVSS base score of 8.0/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-93851?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.