CVE-2026-39976: Laravel Passport TokenGuard Authenticates Unrelated User For Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-349c-2h2f-mxf6",
  "modified" : "2026-04-13T17:48:46Z",
  "published" : "2026-04-08T19:57:55Z",
  "aliases" : [ "CVE-2026-39976" ],
  "summary" : "Laravel Passport: TokenGuard Authenticates Unrelated User for Client Credentials Tokens",
  "details" : "### Impact\nAuthentication 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.\n\n\nUsage of `EnsureClientIsResourceOwner` middleware together with `Passport::$clientUuids` set to `false`, can result in resolving the user instead, as stated in the [documentation](https://laravel.com/docs/13.x/passport#:~:text=The%20underlying%20OAuth2,client%20credentials%20token). \n\n> The [underlying OAuth2 server](https://oauth2.thephpleague.com/database-setup/#:~:text=Please%20note%20that,the%20bearer%20token.) sets the token's sub claim to the client's identifier for client credentials tokens. By default, Passport uses UUIDs for clients, so this cannot collide with a user's integer primary key. However, if you have set Passport::$clientUuids to false, a client credentials token may inadvertently resolve a user whose ID matches the client's ID. In such cases, using this middleware cannot guarantee that the incoming token is a client credentials token.\n\n### Patches\nPatched in v13.7.1\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\nDisallow usage of `client_credentials`. \n\n\n### References\n- https://github.com/laravel/passport/issues/1900\n- https://github.com/laravel/passport/pull/1901\n- https://github.com/laravel/passport/pull/1902\n- https://github.com/thephpleague/oauth2-server/issues/1456#issuecomment-2734989996",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "laravel/passport"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "13.0.0"
      }, {
        "fixed" : "13.7.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/laravel/passport/security/advisories/GHSA-349c-2h2f-mxf6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39976"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/laravel/passport/issues/1900"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/thephpleague/oauth2-server/issues/1456#issuecomment-2734989996"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/laravel/passport/pull/1901"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/laravel/passport/pull/1902"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/laravel/passport"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T19:57:55Z",
    "nvd_published_at" : "2026-04-09T17:16:31Z"
  }
}