Ref - bugtraq post as above.
researcher - SpC-x
the claimed affected version 4.1.3 has calendar.php:
require_once('./private/ltw_config.php');
require_once($ltw_config['include_dir'].'/ltw_classes.php');
and - are you sitting down? - ltw_config.php says:
$ltw_config['include_dir'] = './private';
- Steve