Websense, when configured to permit access to the dynamic content category, allows local users to bypass intended blocking of the Uncategorized category by appending a "/?" sequence to a URL.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25980
http://www.securityfocus.com/archive/1/431685/100/0/threaded
http://www.securityfocus.com/archive/1/431600/100/0/threaded