Summary
Doorkeeper Openid Connect: Dynamic Client Registration feature creates public clients with client_secret
Workarounds
Upgrade existing applications created with a Dynamic Client registration to have confidential: true
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
- Enable dynamic client registration in the initializer
- POST /oauth/registration with client_name, redirect_uris, and scope
- Observe: response returns client_secret, but the created
Doorkeeper::Application has confidential: false - Call
Doorkeeper::Application.by_uid_and_secret(client_id, nil), it
returns the application (credentials bypass) - 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
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Patched in 1.10.0
Frequently Asked Questions
- What is CVE-2026-44476? CVE-2026-44476 is a medium-severity security vulnerability in doorkeeper-openid_connect (rubygems), affecting versions = 1.9.0. It is fixed in 1.10.0.
- Which versions of doorkeeper-openid_connect are affected by CVE-2026-44476? doorkeeper-openid_connect (rubygems) versions = 1.9.0 is affected.
- Is there a fix for CVE-2026-44476? Yes. CVE-2026-44476 is fixed in 1.10.0. Upgrade to this version or later.
- Is CVE-2026-44476 exploitable, and should I be worried? Whether CVE-2026-44476 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-44476 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-44476? Upgrade
doorkeeper-openid_connectto 1.10.0 or later.