A public claim by hackers that Mozilla's Firefox browser is vulnerable to multiple code execution vulnerabilities <A HREF="http://www.eweek.com/article2/0,1895,2023762,00.asp?kc=EWLINEMNL100306EOAD">may be an overblown hoax.</A> On the heels of a ToorCon presentation where two security researchers--Mischa Spiegelmock and Andrew Wbeelsoi--warned that Firefox's implementation of JavaScript was badly flawed and could allow PC takeover attacks, Mozilla's engineers say the risk is limited to a denial-of-service issue. Spiegelmock, a developer at Six Apart, a blog software company in San Francisco, now says the ToorCon talk was meant "to be humorous" and insists the code presented at the conference cannot result in code execution.