CVE-2024-39830: Mattermost

Medium severity, CVSS 5.9. EPSS: 0.4% chance of exploitation in the next 30 days.

Mattermost versions 9.8.x <= 9.8.0, 9.7.x <= 9.7.4, 9.6.x <= 9.6.2 and 9.5.x <= 9.5.5, when shared channels are enabled, fail to use constant time comparison for remote cluster tokens which allows an attacker to retrieve the remote cluster token via a timing attack during remote cluster token comparison.

Affected products

• Mattermost Mattermost: from 9.5.0, before 9.5.6 (fixed in 9.5.6); from 9.6.0, before 9.6.3 (fixed in 9.6.3); from 9.7.0, before 9.7.5 (fixed in 9.7.5); from 9.8.0, before 9.8.1 (fixed in 9.8.1)

Published 2024-07-03. Last modified 2026-06-17.