@font-face {
    font-family: "Special Font";
    src: url("<%= Request.Url.GetLeftPart(UriPartial.Authority) + "/fonts/specialfont.ttf" %>");
}

<?xml version="1.0" encoding="utf-8"?>
    <configuration>
        <system.webServer>
            <httpProtocol>
                <customHeaders>
                    <add name="Access-Control-Allow-Origin" value="*" />
                </customHeaders>
            </httpProtocol>
        </system.webServer>
</configuration>

<configuration>
  <location path="fonts/specialfont.ttf">
    <system.webServer>
       <httpProtocol>
          <customHeaders>
             <add name="Access-Control-Allow-Origin" value="*" />
          </customHeaders>
       </httpProtocol>
    </system.webServer>
  </location>
</configuration>