Rails before 1.2.4, as used for Ruby on Rails, allows remote attackers and ActiveResource servers to determine the existence of arbitrary files and read arbitrary XML files via the Hash.from_xml (Hash#from_xml) method, which uses XmlSimple (XML::Simple) unsafely, as demonstrated by reading passwords from the Pidgin (Gaim) .purple/accounts.xml file.

Session fixation vulnerability in Rails before 1.2.4, as used for Ruby on Rails, allows remote attackers to hijack web sessions via unspecified vectors related to "URL-based sessions."