CVE-2013-0334: Remote code execution

Any Gemfile with multiple top-level source lines cannot reliably control the gem server that a particular gem is fetched from. As a result, Bundler might install the wrong gem if more than one source provides a gem with the same name. This is especially possible in the case of Github’s legacy gem server, hosted at gems.github.com. An attacker might create a malicious gem on Rubygems.org with the same name as a commonly-used Github gem. From that point forward, running bundle install might result in the malicious gem being used instead of the expected gem.