Mattermost 10.11.x <=10.11.10 Permission Validation Flaw in Roles API
CVE-2026-26230 Published on March 16, 2026
Team Admin Privilege Escalation to Demote Members to Guest
Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531
Vulnerability Analysis
CVE-2026-26230 is exploitable with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-26230 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-26230
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Affected Versions
Mattermost:- Version 10.11.0, <= 10.11.10 is affected.
- Version 11.4.0 is unaffected.
- Version 10.11.11 is unaffected.