source: https://www.securityfocus.com/bid/30867/info

Mono is prone to a vulnerability that allows attackers to inject arbitrary HTTP headers because it fails to sanitize input.

By inserting arbitrary headers into an HTTP response, attackers may be able to launch cross-site request-forgery, cross-site scripting, HTTP-request-smuggling, and other attacks.

This issue affects Mono 2.0 and earlier. 

<script runat="server"> void Page_Load(object o, EventArgs e) { // Query parameter text is not checked before saving in user cookie NameValueCollection request = Request.QueryString; // Adding cookies to the response Response.Cookies["userName"].Value = request["text"]; } </script>