CVE-2024-42406: Mattermost Server

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

Mattermost versions 9.11.x <= 9.11.0, 9.10.x <= 9.10.1, 9.9.x <= 9.9.2 and 9.5.x <= 9.5.8 fail to properly authorize requests when viewing archived channels is disabled, which allows an attacker to retrieve post and file information about archived channels. Examples are flagged or unread posts as well as files.

Affected products

• Mattermost Mattermost Server: from 9.5.0, before 9.5.9 (fixed in 9.5.9); from 9.9.0, before 9.9.3 (fixed in 9.9.3); from 9.10.0, before 9.10.2 (fixed in 9.10.2); version 9.11.0 only

Published 2024-09-26. Last modified 2026-06-17.