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4.2
MEDIUM CVSS 3.1
CVE-2026-70665
Doorkeeper OpenID Connect: DCR endpoint persists unvalidated client-supplied scopes
Overview
Description

Doorkeeper OpenID Connect implements an OpenID Connect authentication provider for Rails applications on top of Doorkeeper. Prior to 1.10.4, the Dynamic Client Registration (DCR) endpoint persists client-supplied scopes without validating them against the server's configured scope set. Under certain conditions, this allows a self-registered client to obtain scopes beyond what the server intended to grant. In DynamicClientRegistrationController#application_params, the scopes attribute is assigned directly from params[:scope] with no validation against Doorkeeper.configuration.scopes or optional_scopes. Combined with enforce_configured_scopes being off by default and Doorkeeper's ScopeChecker prioritizing application-level scopes over server-level scopes, this creates a privilege escalation path. This issue is fixed in version 1.10.4.

Details
INFO

Published Date :

Aug. 25, 2026, 11:17 p.m.

Last Modified :

Sept. 9, 2026, 9:09 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-70665 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Openid openid_connect
: Total Affected Vendor : 1 | Products : 1
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 MEDIUM [email protected]
CVSS 3.1 MEDIUM MITRE-CVE
Solution
Update Doorkeeper to version 1.10.4 or later to fix client scope validation.
  • Update Doorkeeper to version 1.10.4.
  • Validate client scopes against server configuration.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-70665.

URL Resource
https://github.com/doorkeeper-gem/doorkeeper-openid_connect/commit/24c3cb1729b69f48649a6f4491dcae69f805000d
https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-8r7r-wh7x-27ff
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-70665 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-70665 weaknesses.

CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs Accessing Functionality Not Properly Constrained by ACLs CAPEC-5: Blue Boxing Blue Boxing CAPEC-13: Subverting Environment Variable Values Subverting Environment Variable Values CAPEC-17: Using Malicious Files Using Malicious Files CAPEC-39: Manipulating Opaque Client-based Data Tokens Manipulating Opaque Client-based Data Tokens CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-51: Poison Web Service Registry Poison Web Service Registry CAPEC-59: Session Credential Falsification through Prediction Session Credential Falsification through Prediction CAPEC-60: Reusing Session IDs (aka Session Replay) Reusing Session IDs (aka Session Replay) CAPEC-76: Manipulating Web Input to File System Calls Manipulating Web Input to File System Calls CAPEC-77: Manipulating User-Controlled Variables Manipulating User-Controlled Variables CAPEC-87: Forceful Browsing Forceful Browsing CAPEC-104: Cross Zone Scripting Cross Zone Scripting CAPEC-127: Directory Indexing Directory Indexing CAPEC-402: Bypassing ATA Password Security Bypassing ATA Password Security CAPEC-647: Collect Data from Registries Collect Data from Registries CAPEC-668: Key Negotiation of Bluetooth Attack (KNOB) Key Negotiation of Bluetooth Attack (KNOB)

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-70665 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-70665 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by [email protected]

    Aug. 27, 2026

    Action Type Old Value New Value
    Added Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/commit/24c3cb1729b69f48649a6f4491dcae69f805000d
    Added Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-8r7r-wh7x-27ff
    Removed Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/commit/24c3cb1729b69f48649a6f4491dcae69f805000d
    Removed Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-8r7r-wh7x-27ff
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Aug. 27, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2026-70665', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-27T13:52:58.639766Z'}
  • New CVE Received by [email protected]

    Aug. 25, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'doorkeeper-gem', 'product': 'doorkeeper-openid_connect', 'versions': [{'status': 'affected', 'version': '< 1.10.4'}]}]
    Added Description Doorkeeper OpenID Connect implements an OpenID Connect authentication provider for Rails applications on top of Doorkeeper. Prior to 1.10.4, the Dynamic Client Registration (DCR) endpoint persists client-supplied scopes without validating them against the server's configured scope set. Under certain conditions, this allows a self-registered client to obtain scopes beyond what the server intended to grant. In DynamicClientRegistrationController#application_params, the scopes attribute is assigned directly from params[:scope] with no validation against Doorkeeper.configuration.scopes or optional_scopes. Combined with enforce_configured_scopes being off by default and Doorkeeper's ScopeChecker prioritizing application-level scopes over server-level scopes, this creates a privilege escalation path. This issue is fixed in version 1.10.4.
    Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
    Added CWE CWE-285
    Added Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/commit/24c3cb1729b69f48649a6f4491dcae69f805000d
    Added Reference https://github.com/doorkeeper-gem/doorkeeper-openid_connect/security/advisories/GHSA-8r7r-wh7x-27ff
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 4.2
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact