.ASPXAUTH cookie being send many times by IE and asp .net fails to authenticate

Question

I'm using MVC3 and I use the following code to authenticate users:

        var host = HttpContext.Current.Request.Url.Host;
        Match match = Regex.Match(host, "([^.]+\\.[^.]{1,3}(\\.[^.]{1,3})?)$");
        string domain = match.Groups[1].Success ? match.Groups[1].Value : host;

        HttpCookie authcookie = FormsAuthentication.GetAuthCookie(userName, rememberMe);
        authcookie.Domain = domain;
        HttpContext.Current.Response.AppendCookie(authcookie);

        if (!string.IsNullOrEmpty(returnUrl))
            HttpContext.Current.Response.Redirect(returnUrl);

It works fine on Chrome, but I have a problem on IE11. IE sends old and new .ASPXAUTH cookies and asp fails to authenticate users:

Whats wrong with the code or the logic?

Answer 1

Your ASP.NET version is not up to date on the latest patches and doesn't recognize IE11 as a browser that supports cookies.

If you don't have any control over the server you can change the <forms ...> element in your web.config file and add cookieless="UseCookies" to it.

More info about the patches on Scott Hanselman's blog.