Wordpress Remote Admin Password Reset Vulnerability

The password of my Wordpress admin account was not valid when I tried to login today. I first thought it was a problem with the LastPass password manager and tried to see if I was still logged into the service. When I checked my email inbox I noticed that I have received a new password for the account. That was strange since I did not request a new password. It was not that much of a concern to me as I thought that someone might have used the password reset functionality to reset the password which meant that physical access to the new password was not possible. - Martin

A new post appeared on the Wordpress discussion list today revealing more details about the process. Everyone is apparently able to reset a Wordpress password if the email address of the Wordpress user is known. All that needs to be done is to point the web browser at http://www.domain.com/wp-login.php?action=lostpassword to reset the password. The email address of the account holder has to be supplied in the form. Wordpress usually will send a confirmation email first asking the email account owner if the password should be reset. The vulnerability manipulates the query to skip this step.

It is not possible to exploit this vulnerability further which means attackers cannot get access to the user account. It can however be theoretically be used to reset the password regularly to lock the user or admin out of the Wordpress blog.

A temporary fix for the remote admin password reset vulnerability was posted. Wordpress administrators need to change one line of code in the wp-login.php file of the Wordpress installation to protect their blog from the attack.

Replace

if ( empty( $key ) )

With

if ( empty( $key ) || is_array( $key ) )

It is advised to apply the temporary fix as soon as possible to Wordpress installations.

Update: The Wordpress team has nevertheless released Wordpress 2.8.4. as a response to the security vulnerability. The new release patches this vulnerability and is a recommended update for every Wordpress installation. Wordpress admins should head over to the Wordpress website to download the new version as of now.