CVE-2026-39976 HIGH

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

Vendor Laravel
Product passport
Weakness CWE-287 · Improper authentication
Published April 9, 2026
Last update April 9, 2026

CVSS base score

7.1/10
Attack vector Network
Attack complexity High
Privileges required Low
User interaction None
Confidentiality High
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N

What the vulnerability does

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.

Key dates

Disclosure timeline

April 9, 2026 CVE published
April 9, 2026 Record updated