Authentication Bypass Vulnerability in Mattermost by Mattermost
CVE-2025-12421

9.9CRITICAL

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
27 November 2025

What is CVE-2025-12421?

Mattermost versions 11.0.x up to 11.0.2, 10.12.x up to 10.12.1, 10.11.x up to 10.11.4, and 10.5.x up to 10.5.12 have a security flaw that permits authenticated users to execute an account takeover. This occurs due to improper verification of the authentication token during code exchange, especially when transitioning between authentication methods. The vulnerability can be exploited specifically if the ExperimentalEnableAuthenticationTransfer feature is enabled and RequireEmailVerification is disabled.

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Affected Version(s)

Mattermost 11.0.0 <= 11.0.2

Mattermost 10.12.0 <= 10.12.1

Mattermost 10.11.0 <= 10.11.4

References

https://mattermost.com/security-updates

CVSS V3.1

Score:
9.9
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

daw10
JSON
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