Cross-site scripting (XSS) vulnerability in the strip_tags helper in actionpack/lib/action_controller/vendor/html-scanner/html/node.rb in Ruby on Rails before 2.3.13, 3.0.x before 3.0.10, and 3.1.x before 3.1.0.rc5 allows remote attackers to inject arbitrary web script or HTML via a tag with an invalid name.