This bug could easily be controlled by attackers, allowing them to completely crash any system that is not updated with the new patch. It could also give attackers the chance to trick the Firefox browser into running other malicious code.
Firefox 1.5 users will soon start to receive the corrective patches along with the automatic updates that run through the browser. Firefox 1.0 and Mozilla 1.7 users will not be affected.
As of May 2, Mozilla reported that they are doing all they can to speed up the process of the fixes and get them released to all Firefox users as soon as possible. So, if you are in the category of possibly being affected by the flaw, hang in there, because help is on the way.