IIS not sending ASP.Net cookies to IE10 (and only to IE10)

asp.netcookieiisinternet exploreruseragent

I have IIS 7.5 server running ASP.Net application, which for some reason doesn't send ASP.Net authentication cookies to IE10. This happens only when request comes in from IE10 browser and only over network (i.e. not when browsing from web server itself). All other browsers (Firefox, Chrome, Safari, IE9) work absolutely fine.

The problem is clearly in browser identification, because when I switch IE10 into IE9 mode, the cookie does arrive. On the other hand, when I force other browsers (for example Firefox) to impersonate IE10 using agent-overriding plug-ins, the cookie is not sent.

This happens regardless of the protocol (http vs https) and server's host name (happens with IP address as well).

So far I ruled out the problem in the server application code, because I have similar setup on another IIS with exact same application, which doesn't exhibit the symptoms, so I assume it's likely something in IIS configuration. By comparing IIS configurations between two systems, I only see the following difference which is possibly relevant: 

<system.web>
  <clientTarget>
    <add alias="ie5" userAgent="Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 4.0)" />
    <add alias="ie4" userAgent="Mozilla/4.0 (compatible; MSIE 4.0; Windows NT 4.0)" />
    <add alias="uplevel" userAgent="Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.1)" />
    <add alias="downlevel" userAgent="Generic Downlevel" />
  </clientTarget>
</system.web>

I want to try to change these settings, but I can't find what this corresponds to in IIS Manager UI.

Best Answer

(Converting comment to answer)

I ran into an issue with IE10 and my ASP.Net application which turned out to be a bug in ASP.Net, except my symptoms had nothing to do with cookies. It was driving me insane because it would only happen on one of the servers. I ran into this article by Scott Hanselman, and applied the hotfix to the server. The hotfix has now been shipped as a regular update. It's a stretch, but maybe you should try running updates on your server.

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