CVE-2025-12421

Mattermost suffers an authentication-tampering vulnerability (CVE-2025-12421) where the token used during code exchange is not verified to originate from the same authentication flow. Affected versions include 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, and 10.5.x