[XSS]

inject

src

<script src="hook.js"></script>
<?php
echo $_GET["payload"];
?>

<h1> inject </h1>
<form>
    <input type="text" name="payload" placeholder="your payload here">
    <input type="submit" value="GO">
</form>

<h1> src </h1>
<?php highlight_string(file_get_contents(basename(__FILE__))); ?>