critical9.9
CVE-2025-12421
Mattermost fails to to verify the token used during code exchange
Impact
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email address used when switching authentication methods and sending a request to the /users/login/sso/code-exchange endpoint. The vulnerability requires ExperimentalEnableAuthenticationTransfer to be enabled (default: enabled) and RequireEmailVerification to be disabled (default: disabled).
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20251022210333-acda1fb5dd46 | 8.0.0-20251022210333-acda1fb5dd46 |
| go | github.com/mattermost/mattermost-server | >= 11.0.0, < 11.0.3 | 11.0.3 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.5.0 before 10.5.13 from 10.11.0 before 10.11.5 from 10.12.0 before 10.12.2 from 11.0.0 before 11.0.3 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://mattermost.com/security-updates
- https://github.com/advisories/GHSA-mp6x-97xj-9x62
- https://nvd.nist.gov/vuln/detail/CVE-2025-12421
- https://github.com/mattermost/mattermost/commit/5072bbf689a46b3b97b2373f26149f5891396e6b
- https://github.com/mattermost/mattermost/commit/acda1fb5dd46a2f46c76ae67012423c760525eaa
- https://github.com/mattermost/mattermost/commit/f361e7d75a7ab9df5a2106e1ceb919b94b55e41d
- https://github.com/mattermost/mattermost/commit/feb598ed2b7ac3cb78a253b032ad7e4628b0de00