From the guys at wordpress

We’ve fixed a pretty critical vulnerability in WordPress’ core HTML sanitation library, and because this library is used lots of places it’s important that everyone update as soon as possible.

I realize an update during the holidays is no fun, but this one is worth putting down the eggnog for. In the spirit of the holidays, consider helping your friends as well.

This script will search /var/www (changeable in a variable) for any wordpress installs and make sure its upgraded to the latest version.
It will run a backup to /root/wp_upgrade/ of all files and database before doing anything with the site in case of major catastrophe.
It pays to check each site after the upgrade to make sure plugins all worked (and upgrade plugins before the upgrade works also!).

Let me know if you have any bugs at all, or any problems.

Here’s your script to upgrade them all.

wget http://b.ri.mu/files/wordpress-upgrade-3.0.4.sh
bash wordpress-upgrade-3.0.4.sh