CVE-2025-12419

9.9 CRITICAL
Published: November 27, 2025 Modified: December 03, 2025

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 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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://mattermost.com/security-updates
Source: responsibledisclosure@mattermost.com
Vendor Advisory

1 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.9 / 10.0
EPSS (Exploit Probability)
0.1%
18th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

mattermost