{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "doorkeeper-openid_connect"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.9.0"
            },
            {
              "fixed": "1.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.9.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44476"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-290"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-04T14:37:11Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nThe `DynamicClientRegistrationController#register` action hard-codes `confidential: false` when creating applications (dynamic_client_registration_controller.rb:18-25), yet the response includes a client_secret and advertises `token_endpoint_auth_methods_supported: [\"client_secret_basic\", \"client_secret_post\"]`.\n\nBecause Doorkeeper\u0027s `Application.by_uid_and_secret` treats a blank/missing secret as valid for non-confidential (public) clients, an\nattacker who knows only the client_id (which is public information) can authenticate as the dynamically-registered client at the token endpoint.\n\n**Note** that Dynamic Client Registration is opt-in feature which is disabled by default so only projects that explicitly enabled it are affected.\n\n**Steps to Reproduce**\n\n1. Enable dynamic client registration in the initializer\n2. POST /oauth/registration with client_name, redirect_uris, and scope\n3. Observe: response returns client_secret, but the created\nDoorkeeper::Application has confidential: false\n4. Call `Doorkeeper::Application.by_uid_and_secret(client_id, nil)` \u2014 it\nreturns the application (credentials bypass)\n5. POST /oauth/token with grant_type=client_credentials and only\nclient_id (no client_secret) \u2014 the token endpoint issues an access token\nwithout any secret verification\n\n\n### Patches\nPatched in 1.10.0\n\n### Workarounds\nUpgrade existing applications created with a Dynamic Client registration to have `confidential: true`",
  "id": "GHSA-m6vc-f87m-cc2h",
  "modified": "2026-06-09T11:57:55Z",
  "published": "2026-06-04T14:37:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-m6vc-f87m-cc2h"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/doorkeeper-gem/doorkeeper-openid_connect"
    },
    {
      "type": "WEB",
      "url": "https://github.com/doorkeeper-gem/doorkeeper-openid_connect/releases/tag/v1.10.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/doorkeeper-openid_connect/CVE-2026-44476.yml"
    },
    {
      "type": "WEB",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-44476"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Doorkeeper Openid Connect: Dynamic Client Registration feature creates public clients with client_secret"
}