What’s Vulnerable › Vulnerabilities

CVE-2026-39976: Laravel Passport's TokenGuard Authenticates Unrelated User for Client Credentials Tokens

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-09 · updated 2026-10-26
• Weakness: CWE-287

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.

Affected products

• laravel passport: from 13.0.0 before 13.7.1 — fixed in 13.7.1

How to fix

Upgrade to a fixed version: laravel passport 13.7.1. Check the vendor advisory for mitigations.

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/laravel/passport/security/advisories/GHSA-349c-2h2f-mxf6
• https://github.com/thephpleague/oauth2-server/issues/1456#issuecomment-2734989996

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