CVE-2026-3637: Mattermost fails to enforce create_post permission when editing posts
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to check the createpost channel permission during post edit operations which allows an authenticated attacker with revoked posting privileges to modify their existing posts via direct API requests to the post update and patch endpoints.. Mattermost Advisory ID: MMSA-2026-00627
Affected Software
Remediation
Information
Event History
Frequently Asked Questions
What is the severity of CVE-2026-3637?
The severity of CVE-2026-3637 is considered high due to the potential unauthorized access to post editing features.
How do I fix CVE-2026-3637?
To fix CVE-2026-3637, upgrade Mattermost to version 11.5.2 or later, 10.11.14 or later, or 11.4.4 or later.
What versions are affected by CVE-2026-3637?
Mattermost versions 11.5.0 to 11.5.1, 10.11.0 to 10.11.13, and 11.4.0 to 11.4.3 are affected by CVE-2026-3637.
What is the impact of CVE-2026-3637?
The impact of CVE-2026-3637 allows authenticated users with revoked posting privileges to edit posts unlawfully.
Is user authentication sufficient to prevent CVE-2026-3637 exploitation?
No, user authentication is not sufficient as the vulnerability allows attackers with revoked permissions to exploit the editing functionality.