CVE-2026-4286

Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update

Published May 18, 2026 CVSS 3.1 · 3.1 Low EPSS < 1% KEV · Not listed
Description
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

Remediation

Vendor Solution

Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-gvg4-jhmr-6j23 Mattermost doesn't check if {{team_id}} was being changed when updating playbooks
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Description 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
Title Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 3.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
May 18, 2026, 12:41 PM
Reserved
Mar 16, 2026, 4:29 PM
Status
Analyzed
Published
May 18, 2026, 9:16 AM
Modified
Oct 14, 2026, 8:10 PM