CVE-2025-14822: Mattermost Server

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Mattermost versions 10.11.x <= 10.11.8 fail to validate input size before processing hashtags which allows an authenticated attacker to exhaust CPU resources via a single HTTP request containing a post with thousands space-separated tokens

Affected products

• Mattermost Mattermost Server: from 10.11.0, before 10.11.9 (fixed in 10.11.9)

Published 2026-01-16. Last modified 2026-06-17.