Auth bypass in Laravel Passport
CVE-2026-39976
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (31.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Laravel Passport — versions >= 13.0.0, < 13.7.1
Weakness classification (CWE)
References
- github.com/laravel/passport/security/advisories/GHSA-349c-2h2f-mxf6 (Mitigation, Vendor Advisory)
- github.com/laravel/passport/issues/1900 (Exploit, Issue Tracking)
- github.com/thephpleague/oauth2-server/issues/1456 (Patch, Issue Tracking)
- github.com/laravel/passport/pull/1901 (Patch, Issue Tracking)
- github.com/laravel/passport/pull/1902 (Patch, Issue Tracking)
Frequently asked questions
- What is CVE-2026-39976?
- CVE-2026-39976 is a high-severity vulnerability in Laravel Passport, classified under Improper Authentication. CVSS score: 7.1/10. Published 2026-04-09.
- How severe is CVE-2026-39976?
- High severity. CVSS v3 base score is 7.1 out of 10.