CVE-2025-36530: Mattermost Server

Medium severity, CVSS 4.9. EPSS: 0.5% chance of exploitation in the next 30 days.

Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to install unauthorized custom plugins via path traversal in the import functionality, bypassing plugin signature enforcement and marketplace restrictions.

Affected products

• Mattermost Mattermost Server: from 9.11.0, before 9.11.18 (fixed in 9.11.18); from 10.5.0, before 10.5.9 (fixed in 10.5.9); from 10.8.0, before 10.8.4 (fixed in 10.8.4); from 10.9.0, before 10.9.2 (fixed in 10.9.2)

Published 2025-08-21. Last modified 2026-06-17.