GHSA-m6vc-f87m-cc2h

Suggest an improvement
Source
https://github.com/advisories/GHSA-m6vc-f87m-cc2h
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-m6vc-f87m-cc2h/GHSA-m6vc-f87m-cc2h.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-m6vc-f87m-cc2h
Aliases
Downstream
CGA (32)
Published
2026-06-04T14:37:11Z
Modified
2026-06-09T12:00:16Z
Severity
  • 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
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

Database specific 
{
    "cwe_ids":  [
        "CWE-290"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-06-04T14:37:11Z",
    "nvd_published_at":  null,
    "severity":  "MODERATE"
}
References

Affected packages

RubyGems / doorkeeper-openid_connect

Package

Name
doorkeeper-openid_connect
Purl
pkg:gem/doorkeeper-openid_connect

Affected ranges

Type
ECOSYSTEM
Events
Introduced
1.9.0
Fixed
1.10.0

Affected versions

1.*
1.9.0

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-m6vc-f87m-cc2h/GHSA-m6vc-f87m-cc2h.json"