CVE-2025-12421 - CVE House
Back to Database
Status published Critical CVE-2025-12421

Account Takeover via Code Exchange Endpoint

Vulnerability Description

Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email address used when switching authentication methods and sending a request to the /users/login/sso/code-exchange endpoint. The vulnerability requires ExperimentalEnableAuthenticationTransfer to be enabled (default: enabled) and RequireEmailVerification to be disabled (default: disabled).

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

THREAT MONITOR

Am I Vulnerable?

Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2025-12421

Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • daw10

References

More from Mattermost

View All →
CVE-2025-9084
Open redirect in OAuth login
Low 3.1
CVE-2025-9081
IDOR in board file download allows any user to download any file by UUID
Low 3.1
CVE-2025-9079
Admin RCE via prepackaged plugins by way of misconfigured imports directory
High 8
CVE-2025-9078
Weak cache keys lead to post IDOR and link preview poisoning
Medium 4.3
CVE-2025-9076
Mattermost Server exposes sensitive user credentials during shared channel membership synchronization
Medium 6.5

Affected Vendor

Affected Software

Mattermost
Vulnerable Versions:
11.0.0, 10.12.0, 10.11.0, 10.5.0, 11.1.0, 11.0.3, 10.12.2, 10.11.5, 10.5.13

Timeline

Official Publish: November 27th, 2025
Last Modified: February 26th, 2026
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Weaknesses (CWE)

CWE-303

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.