Algorithmic complexity vulnerability in Gem::Version::VERSION_PATTERN in lib/rubygems/version.rb in RubyGems before 1.8.23.1, 1.8.24 through 1.8.25, 2.0.x before 2.0.8, and 2.1.x before 2.1.0, as used in Ruby 1.9.0 through 2.0.0p247, allows remote attackers to cause a denial of service (CPU consumption) via a crafted gem version that triggers a large amount of backtracking in a regular expression.
http://blog.rubygems.org/2013/09/09/CVE-2013-4287.html
http://rhn.redhat.com/errata/RHSA-2013-1427.html
http://rhn.redhat.com/errata/RHSA-2013-1441.html
http://rhn.redhat.com/errata/RHSA-2013-1523.html
http://rhn.redhat.com/errata/RHSA-2013-1852.html
http://rhn.redhat.com/errata/RHSA-2014-0207.html
http://secunia.com/advisories/55381