CVE-2017-18911: Mattermost Server

Critical severity, CVSS 9.1. EPSS: 0.7% chance of exploitation in the next 30 days.

An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. The X.509 certificate validation can be skipped for a TLS-based e-mail server.

Affected products

• Mattermost Mattermost Server: before 3.6.7 (fixed in 3.6.7); from 3.7.0, before 3.7.5 (fixed in 3.7.5); from 3.8.0, before 3.8.2 (fixed in 3.8.2)

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