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GHSA-M6VC-F87M-CC2H

Vulnerability from github – Published: 2026-06-04 14:37 – Updated: 2026-06-09 11:57

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

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

Patches

Patched in 1.10.0

Workarounds

Upgrade existing applications created with a Dynamic Client registration to have confidential: true

Severity

6.3 (Medium)


                  
                    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

Show details on source website

JSON

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{
  "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"
}

CVE-2026-44476 (GCVE-0-2026-44476)

Vulnerability from cvelistv5 – Published: 2026-08-25 22:47 – Updated: 2026-08-26 15:38

Title

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

Summary

Doorkeeper is an OAuth 2 provider for Ruby on Rails. In version 1.9.0, an attacker who knows only a dynamically registered client's client_id, which is public information, can authenticate as that client at the token endpoint and obtain an access token without providing its client_secret. This occurs because the Dynamic Client Registration feature creates applications with confidential: false hard-coded, even though the registration response returns a client_secret and advertises support for the client_secret_basic and client_secret_post authentication methods; since Doorkeeper treats a blank or missing secret as valid for non-confidential (public) clients, the secret is never verified. Only projects that have explicitly enabled Dynamic Client Registration, which is disabled by default, are affected. This issue is fixed in version 1.10.0.

Severity

6.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-26 15:38 UTC

CWE

CWE-287 - Improper Authentication
CWE-1390 - Weak Authentication

Assigner

GitHub_M mitre root Scorecard

References

2 references

URL	Tags
https://github.com/doorkeeper-gem/doorkeeper-open…	x_refsource_CONFIRM
https://github.com/doorkeeper-gem/doorkeeper-open…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
doorkeeper-gem	doorkeeper-openid_connect	Affected: >= 1.9.0, < 1.10.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44476",
                "options": [
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                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-26T15:38:41.089218Z",
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        },
        "references": [
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            "tags": [
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            "url": "https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-m6vc-f87m-cc2h"
          }
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        "title": "CISA ADP Vulnrichment"
      }
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    "cna": {
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          "product": "doorkeeper-openid_connect",
          "vendor": "doorkeeper-gem",
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            }
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Doorkeeper is an OAuth 2 provider for Ruby on Rails. In version 1.9.0, an attacker who knows only a dynamically registered client\u0027s client_id, which is public information, can authenticate as that client at the token endpoint and obtain an access token without providing its client_secret. This occurs because the Dynamic Client Registration feature creates applications with confidential: false hard-coded, even though the registration response returns a client_secret and advertises support for the client_secret_basic and client_secret_post authentication methods; since Doorkeeper treats a blank or missing secret as valid for non-confidential (public) clients, the secret is never verified. Only projects that have explicitly enabled Dynamic Client Registration, which is disabled by default, are affected. This issue is fixed in version 1.10.0."
        }
      ],
      "metrics": [
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          "cvssV4_0": {
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            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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