CVE-2025-12419 CRITICAL

CVE-2025-12419: Account takeover on OAuth/OpenID-enabled servers

Vendor Mattermost
Product Mattermost
Weakness CWE-303
Published November 27, 2025
Last update February 26, 2026
View on NVD All CVEs

CVSS base score

9.9/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

November 27, 2025 CVE published
February 26, 2026 Record updated