WordPress has released an important update to its version 3.0.
This WordPress update is said to be critical by their development team.
It fixes a security bug in KSES (a HTML sanitary library).
This bug was discovered by Mauro Gentile and Jon Cave.
If you are a developer, you can look at the changes done by WordPress team here.
How to upgrade WordPress
The best way to upgrade WordPress is by using a plugin WordPress Automatic Upgrade to upgrade the WordPress.
Alternatively, you can also Download WordPress 3.0.3