The Square Squash allows remote attackers to execute arbitrary code via a YAML document in the (1) namespace parameter to the deobfuscation function or (2) sourcemap parameter to the sourcemap function in app/controllers/api/v1_controller.rb.
https://exchange.xforce.ibmcloud.com/vulnerabilities/86335
http://ceriksen.com/2013/08/06/squash-remote-code-execution-vulnerability-advisory/