CVE-2026-118669

Name of the Vulnerable Software and Affected Versions OAuthLib versions prior to 4.0.0

Description In the client credentials and Resource Owner Password Credentials token grant handlers, the system can authenticate request.client as one confidential client while retaining an attacker-supplied request.client id for validate grant type and validate scopes. This allows a lower-privilege authenticated client to cause grant and scope authorization to use another client's identity if the application validator relies on the client id argument, which may result in the issuance of tokens with unauthorized grants or scopes. Validators that authorize exclusively from request.client may not be affected.

Recommendations Update to version 4.0.0.