CVE-2025-12421

CriticalMedium RiskPatched

Mattermost Authentication Bypass

CVSS Score

9.9

Severity

Critical

Available Package Updates

Gogithub.com/mattermost/mattermost/server/v8v8.0.0-20251022210333-acda1fb5dd46View on Go →
Gogithub.com/mattermost/mattermost-serverv11.0.3View on Go →

Fixed in: github.com/mattermost/mattermost/server/v8 (Go): 8.0.0-20251022210333-acda1fb5dd46; github.com/mattermost/mattermost-server (Go): 11.0.3

Exploit Intelligence

Weaponized

No

Detectable

Yes

CISA KEV

Not Listed

Risk Level

Medium Risk

Detection Sources

osv

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Published: 11/27/2025