source: https://www.securityfocus.com/bid/15632/info

BosDates is prone to multiple SQL injection vulnerabilities. These issues are due to a failure in the application to properly sanitize user-supplied input before using it in an SQL query.

Successful exploitation could result in a compromise of the application, disclosure or modification of data, or may permit an attacker to exploit vulnerabilities in the underlying database implementation.

Versions 4.0 and prior are vulnerable; other versions may also be affected. 

http://www.example.com/calendar.phptype=day&calendar=&category=&day=25&month=11&year=[SQL]

http://www.example.com/calendar.php?type=day&calendar=
&category=[SQL]