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).
References
History

Fri, 28 Nov 2025 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Fri, 28 Nov 2025 09:00:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Thu, 27 Nov 2025 18:00:00 +0000

Type Values Removed Values Added
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).
Title Account Takeover via Code Exchange Endpoint
Weaknesses CWE-303
References
Metrics cvssV3_1

{'score': 9.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published: 2025-11-27T17:47:04.944Z

Updated: 2025-11-28T14:52:19.096Z

Reserved: 2025-10-28T16:54:12.491Z

Link: CVE-2025-12421

cve-icon Vulnrichment

Updated: 2025-11-28T14:52:13.431Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2025-11-27T18:15:46.223

Modified: 2025-11-28T23:11:55.537

Link: CVE-2025-12421

cve-icon Redhat

No data.