source: https://www.securityfocus.com/bid/37710/info Ruby WEBrick is prone to a command-injection vulnerability because it fails to adequately sanitize user-supplied input in log files. Attackers can exploit this issue to execute arbitrary commands in a terminal. Versions *prior to* the following are affected: Ruby 1.8.6 patchlevel 388 Ruby 1.8.7 patchlevel 249 Ruby 1.9.1 patchlevel 378 The following example is available: % xterm -e ruby -rwebrick -e 'WEBrick::HTTPServer.new(:Port=>8080).start' & % wget http://www.example.com:8080/%1b%5d%32%3b%6f%77%6e%65%64%07%0a