SPRIND Yubico Independent Researcher Authlete This document describes best current security practice for OAuth 2.0. It updates and extends the threat model and security advice given in RFC 6749, RFC 6750, and RFC 6819 to incorporate practical experiences gathered since OAuth 2.0 was published and covers new threats relevant due to the broader application of OAuth 2.0. Further, it deprecates some modes of operation that are deemed less secure or even insecure.