CVE-2023-3581: Mattermost Server

High severity, CVSS 8.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Mattermost fails to properly validate the origin of a websocket connection allowing a MITM attacker on Mattermost to access the websocket APIs.

Affected products

• Mattermost Mattermost Server: from 7.8.0, before 7.8.7 (fixed in 7.8.7); from 7.9.0, before 7.9.5 (fixed in 7.9.5); from 7.10.0, before 7.10.3 (fixed in 7.10.3)

Published 2023-07-17. Last modified 2026-06-17.