WordPress MU 2.8.4 has been released which fixes a major security problem.
This MU version contains the same bugfix as WordPress 2.8.4.
WordPress MU is a multi user or multi blog version of WordPress that is used to run sites like WordPress.com.
Yesterday a vulnerability was discovered: a specially crafted URL could be requested that would allow an attacker to bypass a security check to verify a user requested a password reset. As a result, the first account without a key in the database (usually the admin account) would have its password reset and a new password would be emailed to the account owner. This doesn’t allow remote access, but it is very annoying.
If you`re running WPMU 2.8.3 you should be able to use the built-in upgrade tool. Else try this.
Wordpress MU 2.8.4a has been released which fixes a small thing
download available from http://mu.wordpress.org/download/