(1) DL and (2) Fiddle in Ruby 1.9 before 1.9.3 patchlevel 426, and 2.0 before 2.0.0 patchlevel 195, do not perform taint checking for native functions, which allows context-dependent attackers to bypass intended $SAFE level restrictions.
www.ruby-lang.org/en/news/2013/05/14/taint-bypass-dl-fiddle-cve-2013-2065