CVE-2025-9081: Mattermost Server

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate access controls which allows any authenticated user to download sensitive files via board file download endpoint using UUID enumeration

Affected products

• Mattermost Mattermost Server: from 9.11.0, before 9.11.17 (fixed in 9.11.17); from 10.5.0, before 10.5.9 (fixed in 10.5.9)

Published 2025-09-19. Last modified 2026-06-17.