The WP Users Masquerade plugin for WordPress is vulnerable to authentication bypass in versions up to, and including, 2.0.0. This is due to incorrect authentication and capability checking in the 'ajax_masq_login' function. This makes it possible for authenticated attackers, with subscriber-level permissions and above, to log in as any existing user on the site, such as an administrator.
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.