ActiveRecord in Ruby on Rails before 2.3.17 and 3.x before 3.1.0 allows remote attackers to cause a denial of service or execute arbitrary code via crafted serialized attributes that cause the +serialize+ helper to deserialize arbitrary YAML.
https://puppet.com/security/cve/cve-2013-0277
https://groups.google.com/group/rubyonrails-security/msg/302ec7ce90f13837?dmode=source&output=gplain
http://www.openwall.com/lists/oss-security/2013/02/11/6
http://www.debian.org/security/2013/dsa-2620
http://weblog.rubyonrails.org/2013/2/11/SEC-ANN-Rails-3-2-12-3-1-11-and-2-3-17-have-been-released/
http://support.apple.com/kb/HT5784
http://securitytracker.com/id?1028109
http://secunia.com/advisories/52112
http://lists.opensuse.org/opensuse-updates/2013-03/msg00048.html
http://lists.apple.com/archives/security-announce/2013/Jun/msg00000.html