Phusion Passenger gem before 3.0.21 and 4.0.x before 4.0.5 for Ruby allows local users to cause a denial of service (prevent application start) or gain privileges by pre-creating a temporary "config" file in a directory with a predictable name in /tmp/ before it is used by the gem.
https://bugzilla.redhat.com/show_bug.cgi?id=892813
http://rhn.redhat.com/errata/RHSA-2013-1136.html
http://blog.phusion.nl/2013/05/29/phusion-passenger-4-0-5-released/
http://blog.phusion.nl/2013/05/29/phusion-passenger-3-0-21-released/