Bundler before 1.7, when multiple top-level source lines are used, allows remote attackers to install arbitrary gems by creating a gem with the same name as another gem in a different source.
bundler.io/blog/2014/08/14/bundler-may-install-gems-from-a-different-source-than-expected-cve-2013-0334.html
lists.fedoraproject.org/pipermail/package-announce/2014-October/140609.html
lists.fedoraproject.org/pipermail/package-announce/2014-October/140654.html
lists.fedoraproject.org/pipermail/package-announce/2014-October/140655.html
lists.opensuse.org/opensuse-updates/2015-03/msg00092.html
www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
www.securityfocus.com/bid/70099
security.gentoo.org/glsa/201609-02