Ruby on Rails 2.1 before 2.1.3 and 2.2.x before 2.2.2 does not verify tokens for requests with certain content types, which allows remote attackers to bypass cross-site request forgery (CSRF) protection for requests to applications that rely on this protection, as demonstrated using text/plain.
http://www.vupen.com/english/advisories/2009/2544
http://www.openwall.com/lists/oss-security/2009/12/02/2
http://www.openwall.com/lists/oss-security/2009/11/28/1
http://weblog.rubyonrails.org/2008/11/18/potential-circumvention-of-csrf-protection-in-rails-2-1
http://secunia.com/advisories/38915
http://secunia.com/advisories/36600
http://pseudo-flaw.net/content/web-browsers/form-data-encoding-roundup/
http://lists.opensuse.org/opensuse-security-announce/2010-03/msg00004.html
http://groups.google.com/group/rubyonrails-security/browse_thread/thread/d741ee286e36e301?hl=en