OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. In OAuthLib versions 3.1.1 until 3.2.1, an attacker providing malicious redirect uri can cause denial of service. An attacker can also leverage usage of "uri_validate" functions depending where it is used. OAuthLib applications using OAuth2.0 provider support or use directly "uri_validate" are affected by this issue. Version 3.2.1 contains a patch. There are no known workarounds.