crontab.c in crontab in FreeBSD allows local users to determine the existence of arbitrary directories via a command-line argument composed of a directory name concatenated with a directory traversal sequence that leads to the /etc/crontab pathname.
https://exchange.xforce.ibmcloud.com/vulnerabilities/65900
http://www.securityfocus.com/bid/46604
http://www.securityfocus.com/archive/1/516716/100/0/threaded