Umhum, I don't really understand what the purpose of that file upload is (which may just be due to the fact that I'm far away from being a CF-expert).
Anyway, when I tried it, I got the error "CF: The form field did not contain a file." (of course I changed "Userdata" to the real fieldname in the form).
Another interesting information: I changed the JkLogLevel in Apache from info to debug. This writes the complete data traffic between Apache and coldfusion in hexadecimal to the logfile. There I can see, that the messages are still correct (i.e. they still contain the null bytes).