Persistent Cross-Site Scripting (XSS) in the advancedsetup_websiteblocking.html Website Blocking page of the Actiontec C1000A router with firmware through CAC004-31.30L.95 allows a remote attacker to inject arbitrary HTML into the Website Blocking page by inserting arbitrary HTML into the \'TodUrlAdd\' URL parameter in a /urlfilter.cmd POST request.