A new Firefox patch have been released fixing the denial of service vulnerability which have been discovered in the Firefox 1.5.0.2 : Martijn Wargers and Nick Mott each described crashes that were discovered to ultimately stem from the same root cause: attempting to use a deleted controller context when designMode was turned on. This generally results in crashing the browser, but in theory references to deleted objects can be abused to run malicious code.. The new firefox 1.5.0.3 have been released to fix this issue and keep providing a safe Internet experience for users. It’s very recommanded to upgrade to this new release.