José Carlos Nieto Jarquín has found a vulnerability affecting WordPress 2.5 ONLY. His advisory was released on SecurityFocus yesterday.
Our recent "Secure WordPress Whitepaper Revision" shows the new WordPress SECRET_KEY variable in the ‘wp-config.php’ file. This SECRET_KEY must be set to something random, as specified in the WordPress documentation. If not, it may be possible for an attacker to brute force the default WordPress SALT generation process to gain access to your blog.
The vulnerability has been reported as a Medium risk as it only affects WordPress installations matching a certain criteria. See advisory for more details.
A proof of concept exploit is publicly available. Please ensure that you set your SECRET_KEY in your ‘wp-config.php’ file to something random.
From wp-config.php:
Change SECRET_KEY to a unique phrase. You won't have to remember
it later, so make it long and complicated. You can visit
https://www.grc.com/passwords.htm to get a phrase generated for you,
or just make something up.
define('SECRET_KEY', 'put your unique phrase here');