Ruby (aka CRuby) before 1.8.7-p357 computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table.
archives.neohapsis.com/archives/bugtraq/2011-12/0181.html
blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/391606
jvn.jp/en/jp/JVN90615481/index.html
jvndb.jvn.jp/ja/contents/2012/JVNDB-2012-000066.html
lists.apple.com/archives/security-announce/2012/May/msg00001.html
rhn.redhat.com/errata/RHSA-2012-0069.html
rhn.redhat.com/errata/RHSA-2012-0070.html
secunia.com/advisories/47405
secunia.com/advisories/47822
support.apple.com/kb/HT5281
www.kb.cert.org/vuls/id/903934
www.nruns.com/_downloads/advisory28122011.pdf
www.ocert.org/advisories/ocert-2011-003.html
www.ruby-lang.org/en/news/2011/12/28/denial-of-service-attack-was-found-for-rubys-hash-algorithm/
www.securitytracker.com/id?1026474
exchange.xforce.ibmcloud.com/vulnerabilities/72020