RubyGems before 1.8.23 does not verify an SSL certificate, which allows remote attackers to modify a gem during installation via a man-in-the-middle attack.
rhn.redhat.com/errata/RHSA-2013-1203.html
rhn.redhat.com/errata/RHSA-2013-1441.html
rhn.redhat.com/errata/RHSA-2013-1852.html
www.openwall.com/lists/oss-security/2012/04/20/24
www.ubuntu.com/usn/USN-1582-1
bugzilla.redhat.com/show_bug.cgi?id=814718
github.com/rubygems/rubygems
github.com/rubygems/rubygems/blob/1.8/History.txt
github.com/rubygems/rubygems/commit/d4c7eafb8efe1e13a7abf5be5a5b4548870b15b7
github.com/rubysec/ruby-advisory-db/blob/master/gems/rubygems-update/CVE-2012-2126.yml
nvd.nist.gov/vuln/detail/CVE-2012-2126