The "Protect Worksheet" functionality in Mathsoft Mathcad 12 through 13.1, and PTC Mathcad 14, implements file access restrictions via a protection element in a gzipped XML file, which allows attackers to bypass these restrictions by removing this element.
https://exchange.xforce.ibmcloud.com/vulnerabilities/37263
http://www.securityfocus.com/archive/1/482341/100/0/threaded