PHP: How to do session validation with flashupload plugin?

Hi, I upgraded from 2.0.2 to 2.1.1 today, and quickly discovered that uploading with the new flashupload plugin did not work. Disabling the plugin makes upload work again, but I would like to enable the plugin.

The problem, when having the flashupload plugin enabled, is that the session doesn't seem to be available for the CheckAuthentication() function in CKFinder's config.php when accessed from flash. I guess I'm not the only one running into this problem, so perhaps someone has come up with a good solution for it?

Edit: I found this solution, but it's only for ASP.NET. Is there some similar solution for PHP?