The omniauth-weibo-oauth2 gem 0.4.6 for Ruby, as distributed on RubyGems.org, included a code-execution backdoor inserted by a third party. Versions through 0.4.5, and 0.5.1 and later, are unaffected.

Cross-site request forgery (CSRF) vulnerability in the omniauth-oauth2 gem 1.1.1 and earlier for Ruby allows remote attackers to hijack the authentication of users for requests that modify session state.