CVE-2026-39976
Laravel Passport's TokenGuard Authenticates Unrelated User for Client Credentials Tokens
Laravel Passport provides OAuth2 server support to Laravel. From 13.0.0 to before 13.7.1, there is an 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. This vulnerability is fixed in 13.7.1.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Laravel Passport's TokenGuard Authenticates Unrelated User for Client Credentials Tokens
Laravel Passport provides OAuth2 server support to Laravel. From 13.0.0 to before 13.7.1, there is an 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. This vulnerability is fixed in 13.7.1.
- Record
CVE-2026-39976- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
EUVDEUVD-2026-20970
Laravel Passport provides OAuth2 server support to Laravel. From 13.0.0 to before 13.7.1, there is an 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. This vulnerability is fixed in 13.7.1.
- Record
EUVD-2026-20970- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-349c-2h2f-mxf6
Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens
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::$clientUuids set to false, can result in resolving the user instead, as stated in the documentation.
The underlying OAuth2 server sets the token's sub claim to the client's identifier for client credentials tokens. By default, Passport uses UUIDs for clients, so this cannot collide with a user's integer primary key. However, if you have set Passport::$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 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
- Record
GHSA-349c-2h2f-mxf6- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
NVD
Laravel Passport provides OAuth2 server support to Laravel. From 13.0.0 to before 13.7.1, there is an 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. This vulnerability is fixed in 13.7.1.
- Record
CVE-2026-39976- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
OSV
Laravel Passport's TokenGuard Authenticates Unrelated User for Client Credentials Tokens
Laravel Passport provides OAuth2 server support to Laravel. From 13.0.0 to before 13.7.1, there is an 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. This vulnerability is fixed in 13.7.1.
- Record
CVE-2026-39976- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
OSVGHSA-349c-2h2f-mxf6
Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens
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::$clientUuids set to false, can result in resolving the user instead, as stated in the documentation.
The underlying OAuth2 server sets the token's sub claim to the client's identifier for client credentials tokens. By default, Passport uses UUIDs for clients, so this cannot collide with a user's integer primary key. However, if you have set Passport::$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 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
- Record
GHSA-349c-2h2f-mxf6- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N - Weakness
- CWE-287
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
laravel/passportPackagist |
13.0.0 up to 13.7.1 | 13.7.1 |
laravel/passportPackagist |
13.0.0 up to 13.7.1, plus listed versions v13.0.0v13.0.1v13.0.2v13.0.3v13.0.4 Show 15 moreShow lessv13.0.5v13.0.6v13.1.0v13.2.0v13.2.1v13.2.2v13.3.0v13.4.0v13.4.1v13.4.2v13.4.3v13.4.4v13.5.0v13.6.0v13.7.0 |
13.7.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-39976 is a high vulnerability (CVSS 7.1) in Laravel Passport, published April 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.29%, the 22nd percentile. Fixed in laravel/passport 13.7.1.
References
github.com/laravel/passport/security/advisories/GHSA-349c-2h2f-mxf6
nvd.nist.gov/vuln/detail/CVE-2026-39976