Maybe I’m missing something, but wp-uploadfile.php doesn’t appear to be a valid WP file?

Nick, your not missing anything at all. I assume they mean the upload page under wp-admin, however, the advisory is very vague.

It appears to releate to a specific plugin, not wordpress itself.

I tried to look for the plugin mentioned, but no joy, there’s no reference to that file in the official plug-in svn either.