CVE-2026-4055
Unauthorized Playbook Run Creation in Mattermost
Publication date: 2026-05-21
Last updated on: 2026-05-21
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | mattermost | to 11.5.1 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in Mattermost versions 11.5.x up to and including 11.5.1. It occurs because the software fails to properly validate the team-level run_create permission against the target team when creating a playbook run. As a result, an authenticated team member can create runs in teams where they do not have permission by specifying a different team ID in the run creation API request.
How can this vulnerability impact me? :
The impact of this vulnerability is that an authenticated user with limited permissions can create playbook runs in teams where they should not have the ability to do so. This could lead to unauthorized actions or changes within teams, potentially disrupting workflows or causing confusion by allowing users to operate beyond their intended access level.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade Mattermost to a version later than 11.5.1 where the issue has been fixed.
Additionally, monitor Mattermost security updates and advisories regularly to stay informed about patches and fixes.