CVE-2018-21263: Mattermost Server

High severity, CVSS 8.8. EPSS: 0.9% chance of exploitation in the next 30 days.

An issue was discovered in Mattermost Server before 4.7.0, 4.6.2, and 4.5.2. An attacker could authenticate to a different user's account via a crafted SAML response.

Affected products

• Mattermost Mattermost Server: before 4.5.2 (fixed in 4.5.2); from 4.6.0, before 4.6.2 (fixed in 4.6.2); version 4.7.0 only

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