When you have a NULL pointer dereference a code execution is also possible, so you can't exclude it at all. For example in this old flaw: http://securitytracker.com/alerts/2006/Apr/1016001.html "The browser does not properly process certain combinations of nested OBJECT tags. A remote user can create specially crafted HTML that, when loaded by the target user, will trigger a NULL pointer dereference and cause the target user's browser to crash or execute arbitrary code."
