CVE-2018-21248: Mattermost Server

High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days.

An issue was discovered in Mattermost Server before 5.4.0. It mishandles possession of superfluous authentication credentials.

Affected products

• Mattermost Mattermost Server: before 5.4.0 (fixed in 5.4.0)

Published 2020-06-19. Last modified 2026-06-17.