Executive brief
Mattermost, a collaboration and incident response platform, contains a flaw in how it handles permissions for its Playbooks feature. This vulnerability allows users who do not have the appropriate authorization to view public playbooks that should otherwise be restricted. While this does not allow for data modification, it could lead to the unauthorized disclosure of internal workflows and operational procedures.
Technical details
An incorrect authorization vulnerability (CWE-863) exists in Mattermost Server and the Playbooks plugin. The application fails to perform adequate permission checks when a user attempts to access public playbooks via the '/get' endpoint. An authenticated attacker with low privileges can bypass intended access controls to retrieve playbook data they are not authorized to see. The issue is rooted in the Playbooks plugin's handling of category and permission services. Patches have been released in Mattermost Server versions 11.5.2, 11.4.4, and 10.11.14, as well as Playbooks plugin version 1.41.1 (commit 887d9ca).
Affected products
- Mattermost Mattermost Server 11.5.0 to 11.5.1, 11.4.0 to 11.4.3, 10.11.0 to 10.11.13
- Mattermost Mattermost Playbooks Plugin < 1.41.1-0.20260309184833-887d9cacb616
Timeline
- 2026-03-09: patched: Fix committed to Playbooks plugin repository
- 2026-05-18: disclosed: NVD and GitHub Advisory published
- 2026-06-01: advisory: Advisory reviewed and updated