CVE-2025-54499: Mattermost Server

Low severity, CVSS 3.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to use constant-time comparison for sensitive string comparisons which allows attackers to exploit timing oracles to perform byte-by-byte brute force attacks via response time analysis on Cloud API keys and OAuth client secrets

Affected products

• Mattermost Mattermost Server: from 10.5.0, before 10.5.11 (fixed in 10.5.11); from 10.11.0, before 10.11.3 (fixed in 10.11.3)

Published 2025-10-16. Last modified 2026-06-17.