VULNERABILITY INTELLIGENCE

CVE-2026-91629

CVSS score4.7 MEDIUM

EPSS probability0.33%

CISA KEVNot currently listed

Published2026-10-20

Last modified2026-10-26

Description

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continue receiving real-time events until the cached session expires or the client reconnects.. Mattermost Advisory ID: MMSA-2026-00664