High, CVSS 7.1PackagistPublished
Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens
CVE-2026-39976 · GHSA-349c-2h2f-mxf6
- Affected
- Packagist laravel/passport >= 13.0.0, < 13.7.1
- Fixed in
- 13.7.1· Vendor fix available
- Issue
- Impact Authentication Bypass for clientcredentials 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::$clientUuids set to false, can result in resolving the user instead, as stated in the documentation. The underlying OAuth2 server sets the token's sub claim to the client's identifier for client credentials tokens. By default, Passport uses UUIDs for clients, so this cannot collide with a user's integer primary key. However, if you have set Passport::$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…
Recommended action: Upgrade to 13.7.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.