CVE-2026-4286: Mattermost doesn't check if {{team_id}} was being changed when updating playbooks

May 18, 2026 (updated June 1, 2026)

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

References

github.com/advisories/GHSA-gvg4-jhmr-6j23
github.com/mattermost/mattermost-plugin-playbooks/commit/e1d6ec2c94e695fb74e0c0c11c0d45e028bb96f3
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2026-4286

Code Behaviors & Features

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