Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation privileges to take over a user account via manipulation of authentication data during the OAuth completion flow. This requires email verification to be disabled (default: disabled), OAuth/OpenID Connect to be enabled, and the attacker to control two users in the SSO system with one of them never having logged into Mattermost.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-3x39-62h4-f8j6 Mattermost fails to properly validate OAuth state tokens during OpenID Connect authentication
Fixes

Solution

Update Mattermost to versions 11.1.0, 10.12.2, 10.11.5, 10.5.13, 11.0.4 or higher.


Workaround

No workaround given by the vendor.

References
History

Wed, 03 Dec 2025 15:30:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server

Fri, 28 Nov 2025 16:15:00 +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 17:30:00 +0000

Type Values Removed Values Added
Description Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation or admin privileges to take over any user account via manipulation of authentication data during the OAuth completion flow Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation privileges to take over a user account via manipulation of authentication data during the OAuth completion flow. This requires email verification to be disabled (default: disabled), OAuth/OpenID Connect to be enabled, and the attacker to control two users in the SSO system with one of them never having logged into Mattermost.

Thu, 27 Nov 2025 16:00:00 +0000

Type Values Removed Values Added
Description Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation or admin privileges to take over any user account via manipulation of authentication data during the OAuth completion flow
Title Account takeover on OAuth/OpenID-enabled servers
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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2025-12-02T04:55:58.042Z

Reserved: 2025-10-28T16:09:58.730Z

Link: CVE-2025-12419

cve-icon Vulnrichment

Updated: 2025-11-28T15:21:21.369Z

cve-icon NVD

Status : Analyzed

Published: 2025-11-27T16:15:46.957

Modified: 2025-12-03T15:17:16.337

Link: CVE-2025-12419

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-11-28T08:51:24Z

Weaknesses