CVE-2024-39837: Mattermost Server

Medium severity, CVSS 5.4. EPSS: 0.3% chance of exploitation in the next 30 days.

Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6 fail to properly restrict channel creation which allows a malicious remote to create arbitrary channels, when shared channels were enabled.

Affected products

• Mattermost Mattermost Server: from 9.5.0, before 9.5.7 (fixed in 9.5.7); version 9.9.0 only

Published 2024-08-01. Last modified 2026-06-17.