Headline
GHSA-3x39-62h4-f8j6: Mattermost fails to properly validate OAuth state tokens during OpenID Connect authentication
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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- GitHub Advisory Database
- GitHub Reviewed
- CVE-2025-12419
Mattermost fails to properly validate OAuth state tokens during OpenID Connect authentication
Critical severity GitHub Reviewed Published Nov 27, 2025 to the GitHub Advisory Database • Updated Dec 1, 2025
Package
gomod github.com/mattermost/mattermost-server (Go)
Affected versions
>= 10.12.0, < 10.12.2
>= 10.11.0, < 10.11.5
>= 10.5.0, < 10.5.13
>= 11.0.0, < 11.0.4
Patched versions
10.12.2
10.11.5
10.5.13
11.0.4
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-20251028000919-d3ed703dc833
8.0.0-20251028000919-d3ed703dc833
Description
Published to the GitHub Advisory Database
Nov 27, 2025