The value of the redirect request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload ycsz3"><script>alert(1)</script>bn76w was submitted in the redirect parameter. This input was echoed unmodified in the application's response. By using this Java Script injection, the attacker can trick a lot of users into visiting his dangerous URL which is reflected on the login form, before they log in, warning them that there is a problem with the login