NETGEAR FVS318 running firmware 2.4, and possibly other versions, allows remote attackers to bypass the filters using hex encoded URLs, as demonstrated using a hex encoded file extension.
https://exchange.xforce.ibmcloud.com/vulnerabilities/18920
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-0291
http://www.securityfocus.com/bid/12278
http://www.securinews.com/vuln.htm?vulnid=103
http://securitytracker.com/id?1012913
http://secunia.com/advisories/13787
http://marc.info/?l=bugtraq&m=110599727631560&w=2
http://lists.grok.org.uk/pipermail/full-disclosure/2005-January/030984.html