CVE-2026-4055

Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629

Score

CVSS 3.1 4.3 Medium

Status

Analyzed - responsibledisclosure@mattermost.com

Published

2026-05-21

Last modified

2026-05-21

Weaknesses

CWE-863

Affected products

• Mattermost (Mattermost)
• Mattermost Server (Mattermost)

References

• https://mattermost.com/security-updates