CVE-2025-3227: Mattermost Server

Medium severity, CVSS 4.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly enforce channel member management permissions in playbook runs, allowing authenticated users without the 'Manage Channel Members' permission to add or remove users from public and private channels by manipulating playbook run participants when the run is linked to a channel.

Affected products

• Mattermost Mattermost Server: from 9.11.0, before 9.11.16 (fixed in 9.11.16); from 10.5.0, before 10.5.6 (fixed in 10.5.6); from 10.6.0, before 10.6.6 (fixed in 10.6.6); from 10.7.0, before 10.7.3 (fixed in 10.7.3); version 10.8.0 only

Published 2025-06-20. Last modified 2026-06-17.