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GHSA-349c-2h2f-mxf6

Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens

Source: GitHub Advisory Database (reviewed) High CVE-2026-39976

Packages

EcosystemPackageAffectedFixed in
Packagist laravel/passport >= 13.0.0, < 13.7.1 13.7.1

Details

As written in the advisory (Markdown source, shown as plain text).

### Impact Authentication Bypass for `client_credentials` tokens. the league/oauth2-server library sets the JWT sub claim to the client identifier (since there's no user). The token guard then passes this value to retrieveById() without validating it's actually a user identifier, potentially resolving an unrelated real user. Any machine-to-machine token can inadvertently authenticate as an actual user. Usage of `EnsureClientIsResourceOwner` middleware together with `Passport::$clientUuids` set to `false`, can result in resolving the user instead, as stated in the [documentation](https://laravel.com/docs/13.x/passport#:~:text=The%20underlying%20OAuth2,client%20credentials%20token). > The [underlying OAuth2 server](https://oauth2.thephpleague.com/database-setup/#:~:text=Please%20note%20that,the%20bearer%20token.) sets the token's sub claim to the client's identifier for client credentials tokens. By default, Passport uses UUIDs for clients, so this cannot collide with a user's integer primary key. However, if you have set Passport::$clientUuids to false, a client credentials token may inadvertently resolve a user whose ID matches the client's ID. In such cases, using this middleware cannot guarantee that the incoming token is a client credentials token. ### Patches Patched in v13.7.1 ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ Disallow usage of `client_credentials`. ### References - https://github.com/laravel/passport/issues/1900 - https://github.com/laravel/passport/pull/1901 - https://github.com/laravel/passport/pull/1902 - https://github.com/thephpleague/oauth2-server/issues/1456#issuecomment-2734989996

References

External links from the advisory. They lead to third-party sites.