An XSS vulnerability in the "Email Subscribers & Newsletters" plugin 4.1.6 for WordPress allows an attacker to inject malicious JavaScript code through a publicly available subscription form using the esfpx_name wp-admin/admin-ajax.php POST parameter.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.