CVE-2021-37863: Mattermost Server

Medium severity, CVSS 5.7. EPSS: 0.9% chance of exploitation in the next 30 days.

Mattermost 6.0 and earlier fails to sufficiently validate parameters during post creation, which allows authenticated attackers to cause a client-side crash of the web application via a maliciously crafted post.

Affected products

• Mattermost Mattermost Server: up to and including 6.0

Published 2021-12-17. Last modified 2026-06-17.