CVE-2018-21260: Mattermost Server

Low severity, CVSS 2.7. EPSS: 0.7% chance of exploitation in the next 30 days.

An issue was discovered in Mattermost Server before 4.8.1, 4.7.4, and 4.6.3. WebSocket events were accidentally sent during certain user-management operations, violating user privacy.

Affected products

• Mattermost Mattermost Server: from 4.6.0, before 4.6.3 (fixed in 4.6.3); from 4.7.0, before 4.7.4 (fixed in 4.7.4); from 4.8.0, before 4.8.1 (fixed in 4.8.1)

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