The WP Hardening – Fix Your WordPress Security plugin for WordPress is vulnerable to Security Feature Bypass in all versions up to, and including, 1.2.6. This is due to use of an incorrect regular expression within the "Stop User Enumeration" feature. This makes it possible for unauthenticated attackers to bypass intended security restrictions and expose site usernames.
The product specifies a regular expression in a way that causes data to be improperly matched or compared.
The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses.