Two Factor (2FA) Authentication via Email <= 1.9.8 - Two-Factor Authentication Bypass via token

The Two Factor (2FA) Authentication via Email plugin for WordPress is vulnerable to Two-Factor Authentication Bypass in versions up to, and including, 1.9.8. This is because the SS88_2FAVE::wp_login() method only enforces the 2FA requirement if the 'token' HTTP GET parameter is undefined, which makes it possible to bypass two-factor authentication by supplying any value in the 'token' parameter during login, including an empty one.