CVE-2025-13821: Mattermost Server

Medium severity, CVSS 5.7. EPSS: 0.2% chance of exploitation in the next 30 days.

Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. Mattermost Advisory ID: MMSA-2025-00560

Affected products

• Mattermost Mattermost Server: from 10.11.0, before 10.11.10 (fixed in 10.11.10); from 11.1.0, before 11.1.3 (fixed in 11.1.3); from 11.2.0, before 11.2.2 (fixed in 11.2.2)

Published 2026-02-16. Last modified 2026-06-17.