From Slashdot
Firefox 0.10.1 was released today to fix a security flaw that could potentially allow a malicious site to erase files from the user’s Download directory. If you already have Firefox 0.10 installed, you can go to Tools, Options, and choose Advanced, go to Software Updates and choose Check Now to grab the patch.”
This update is painless, just a patch file, takes about five seconds to install.