CVE-2025-13352: Mattermost Server

Low severity, CVSS 3.0. EPSS: 0.2% chance of exploitation in the next 30 days.

Mattermost versions 10.11.x <= 10.11.6 and Mattermost GitHub plugin versions <=2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts.

Affected products

• Mattermost Mattermost Server: from 10.11.0, before 10.11.7 (fixed in 10.11.7)

Published 2025-12-17. Last modified 2026-06-17.