The docs for CGI recommend using the upload method instead of param for uploading files. Just use

     $fh = $query->upload('uploaded_file');
     while (<$fh>) {
           print;
     }
[download]

Instead of printing you should do what you want with the file.

One thing that bit me just recently with CGI was that if you call new twice on it then uploaded files are gone. The filename still comes over, but the file itself is gone. So if you are working in a mod_perl environment, make sure you are calling CGI->new once and only once.