The XMLRPC server in utils.rb for the ruby library (libruby) 1.8 sets an invalid default value that prevents "security protection" using handlers, which allows remote attackers to execute arbitrary commands.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10819
http://www2.ruby-lang.org/en/20050701.html
http://www.securityfocus.com/bid/14016
http://www.redhat.com/support/errata/RHSA-2005-543.html
http://www.novell.com/linux/security/advisories/2005_18_sr.html
http://www.kb.cert.org/vuls/id/684913
http://www.debian.org/security/2005/dsa-748
http://www.ciac.org/ciac/bulletins/p-312.shtml
http://www.auscert.org.au/5509
http://secunia.com/advisories/16920/
http://lists.apple.com/archives/security-announce/2005/Sep/msg00002.html
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=315064
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/5237