GHSA-m6vc-f87m-cc2h

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GHSA-m6vc-f87m-cc2h

Summary: Doorkeeper Openid Connect: Dynamic Client Registration feature creates public clients with client_secret

Details: ### Impact The `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"]`. Because Doorkeeper's `Application.by_uid_and_secret` treats a blank/missing secret as valid for non-confidential (public) clients, an attacker who knows only the client_id (which is public information) can authenticate as the dynamically-registered client at the token endpoint. **Note** that Dynamic Client Registration is opt-in feature which is disabled by default so only projects that explicitly enabled it are affected. **Steps to Reproduce** 1. Enable dynamic client registration in the initializer 2. POST /oauth/registration with client_name, redirect_uris, and scope 3. Observe: response returns client_secret, but the created Doorkeeper::Application has confidential: false 4. Call `Doorkeeper::Application.by_uid_and_secret(client_id, nil)` — it returns the application (credentials bypass) 5. POST /oauth/token with grant_type=client_credentials and only client_id (no client_secret) — the token endpoint issues an access token without any secret verification ### Patches Patched in 1.10.0 ### Workarounds Upgrade existing applications created with a Dynamic Client registration to have `confidential: true`

References: https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-m6vc-f87m-cc2h, https://github.com/doorkeeper-gem/doorkeeper-openid_connect, https://github.com/doorkeeper-gem/doorkeeper-openid_connect/releases/tag/v1.10.0, https://github.com/rubysec/ruby-advisory-db/blob/master/gems/doorkeeper-openid_connect/CVE-2026-44476.yml, https://www.cve.org/CVERecord?id=CVE-2026-44476