A timing side-channel vulnerability exists in the PKCE (RFC 7636) implementation of the Authorization Code Grant flow. The code_challenge_method_plain function uses Python's standard == operator for string comparison instead of a constant-time comparison function, potentially allowing timing-based attacks.
When enable_jsonp=True, oauthlib's RevocationEndpoint reflects the user-supplied callback parameter directly into JavaScript response bodies on both success and error paths without validating that it is a legal JSONP callback name. This allows arbitrary JavaScript response generation instead of a restricted function call, making the documented JSONP revocation feature unsafe for browser-based JSONP consumption when attackers can influence callback.
Attacker providing malicious redirect uri can cause DoS to oauthlib's web application. Attacker can also leverage usage of uri_validate functions depending where it is used. What kind of vulnerability is it? Who is impacted? Oauthlib applications using OAuth2.0 provider support or use directly uri_validate function.