source: https://www.securityfocus.com/bid/9639/info

An SQL injection vulnerability has been reported to affect BosDates calendar system. The issue arises due to insufficient sanitization of user supplied data. As a result of this issue an attacker could modify the logic and structure of database queries. Other attacks may also be possible, such as gaining access to sensitive information.

http://www.example.com/directory/calendar_download.php?calendar=[query]