Mattermost <=11.5.1 & 10.11.13 Playbook Team ID Bypass via PUT API
CVE-2026-4286 Published on May 18, 2026
Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to check if {{team_id}} was being changed when updating playbooks, allowing users with only {{Manage Playbook Configurations}} permission to change a playbook's team, bypassing manage members restriction via PUT api. Mattermost Advisory ID: MMSA-2025-00552
Vulnerability Analysis
CVE-2026-4286 is exploitable with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on 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-2026-4286 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-4286
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Affected Versions
Mattermost:- Version 11.5.0, <= 11.5.1 is affected.
- Version 10.11.0, <= 10.11.13 is affected.
- Version 11.6.0 is unaffected.
- Version 11.5.2 is unaffected.
- Version 10.11.14 is unaffected.