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."

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