Security researchers claim to have discovered a flaw in Firefox that could allow attackers to disable the browser's anti-phishing filter through a simple change in a site's URL syntax.

SecuriTeam, a security alert site maintained by Beyond Security, said that the trick could allow for pages already in the Firefox registry of known phishing sites to slip past the recognition software and appear authentic to the user. 

SecuriTeam credited a report by an independent researcher using the name 'Kanedaaa'. 

The researcher discovered that the phishing filter could be disabled when an extra 'forward slash' is entered after the domain suffix (e.g. www.vnunet.com//news).

Firefox normally responds to a known phishing page by alerting users and redirecting them to a search page.

Mozilla, which oversees development and distribution of the open source browser, did not immediately respond to a request for comment from vnunet.com.