The Security Mentor

This could let your computer be taken over if you view a .GIF image file that a bad guy specially prepared to take advantage of the bug.

This is pretty serious, but last I heard there weren't actual attacks in the wild yet. What makes this bad is that it could happen without any action on your part other than visiting the wrong web page, or even simply visiting a good web page that has the wrong ad on it.

Upgrading is easy and you can do it inside Firefox. Go to the Tools menu, click Options, click Advanced at the bottom left of the dialog that comes up, scroll down to "Software Update" on the right side of the dialog, click the Check Now button and follow instructions.

All the browsers I know of have had some kind of vulnerability show up recently in how they handle images. So why am I recommending Firefox over other browsers? Part of the answer is in this sentence from the vnunet.com article: "The flaw came to light after work done by security researchers at Internet Security Systems but was fixed before they published their report." The Firefox team can move much faster than a large company to fix a problem.