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.
| Package (Ecosystem) | Introduced | Fixed | Limit |
|---|---|---|---|
| github.com/mattermost/mattermost/server/v8(Go) | 0 | 8.0.0-20251028000919-d3ed703dc833 | N/A |
| github.com/mattermost/mattermost-server(Go) | 10.12.0 | 10.12.2 | N/A |
| github.com/mattermost/mattermost-server(Go) | 10.11.0 | 10.11.5 | N/A |
| github.com/mattermost/mattermost-server(Go) | 10.5.0 | 10.5.13 | N/A |
| github.com/mattermost/mattermost-server(Go) | 11.0.0 | 11.0.4 | N/A |
CVSS Metrics
