Unfortunately, even our favorite browser has the occasional security problem. I think the nastiest one was that top one that made it possible to spoof the url shown in the address bar. It wasn't out long, though.
If you haven't patched your copy of Firefox yet, it's really easy to do.
- Open Firefox
- Click Tools, Options...
- Click the Advanced icon on the left
- Scroll down to Software Update
- Make sure Firefox is selected and click the Check Now