CVE-2026-39976 Laravel Passport's TokenGuard Authenticates Unrelated User for Client Credentials Tokens
Attackers can use machine-to-machine tokens to authenticate as unrelated real users due to improper validation of client credentials.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39976?
CVE-2026-39976 is a high-severity authentication bypass vulnerability in laravel passport, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-287
Which versions are affected by CVE-2026-39976?
2 open source packages ship an affected version, including laravel/passport. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
laravel/passport Packagist | From 13.0.0 | 13.7.1 |
laravel/passport Packagist | From 13.0.0 | 13.7.1 |
Products include Laravel Passport.
How do I fix CVE-2026-39976?
Upgrade laravel/passport to 13.7.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-39976 being exploited?
There is no known exploitation of CVE-2026-39976 in the wild and no public exploit code.
Sources
Also known as GHSA-349c-2h2f-mxf6.