laravel/passport security advisory

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

CVE-2026-39976 is a high-severity authentication bypass vulnerability in the PHP package laravel/passport (CVSS 7.1), published 9 April 2026. It is fixed in 13.7.1; earlier versions are affected. Exploiting it needs a low-privilege user account.

high 7.1 published 2026-04-09 · updated 2026-10-26

Affected versions: >= 13.0.0, < 13.7.1
Fixed in: 13.7.1
Newest release: 13.10.0
Severity: High · CVSS 7.1
Type: Authentication bypass
CWE-287
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your laravel/passport version affected?

Run composer show laravel/passport in your project, then enter the version. We check it against this and every other known laravel/passport advisory.

Who can exploit CVE-2026-39976

Access: A normal, low-privilege user account in the app.
Conditions: It only works under specific conditions the attacker does not fully control (CVSS rates the attack as high complexity).

CVSS vector (scored by GitHub): CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N

Your app is only exposed if it uses the affected part of laravel/passport. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-39976 in laravel/passport

Find the installed version: composer show laravel/passport. If you never required it yourself, composer why laravel/passport shows which package pulls it in.
Update it: composer update laravel/passport --with-all-dependencies. You need 13.7.1 or newer.
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "laravel/passport": "^13.7.1" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-39976.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for authentication bypass issues while the upgrade waits. None of it replaces the fix.

Remove accounts you do not need and review what each role can do.
Put the admin area behind a VPN, IP allow-list or extra login until you upgrade.
If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-39976 advisory

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.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-39976. Advisory title: “Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens”.

References

GitHub advisory GHSA-349c-2h2f-mxf6 github.com
Pull request #1901 github.com
Pull request #1902 github.com
github.com github.com
github.com github.com

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Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.