CVE-2025-47871: Mattermost Server

Medium severity, CVSS 5.4. 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 validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive information about linked private channels including channel name, display name, and participant count through the run metadata API endpoint.

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 2025-06-30. Last modified 2026-06-17.