osTicket contains a flaw that may allow a remote attacker to execute arbitrary commands. The issue is due to the main.php script not properly sanitizing user input supplied to the 'include_dir' variable. This may allow an attacker to include a file from a remote host that contains arbitrary commands which will be executed by the vulnerable script.
Upgrade to version 1.3.1 or higher, as it has been reported to fix this vulnerability. In addition, osTicket.com has released a patch for some older versions.