Mattermost fails to to verify the token used during code exchange
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).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2025-12421US | — | — | ||
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 s… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/mattermost/mattermostPACKAGE
- https://github.com/mattermost/mattermost/commit/5072bbf689a46b3b97b2373f26149f5891396e6bWEB
- https://github.com/mattermost/mattermost/commit/acda1fb5dd46a2f46c76ae67012423c760525eaaWEB
- https://github.com/mattermost/mattermost/commit/f361e7d75a7ab9df5a2106e1ceb919b94b55e41dWEB
- https://github.com/mattermost/mattermost/commit/feb598ed2b7ac3cb78a253b032ad7e4628b0de00WEB
- https://mattermost.com/security-updatesWEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-12421ADVISORY
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