Domain Name Relay Daemon (DNRD) before 2.19.1 allows remote attackers to cause a denial of service (infinite recursion) via a DNS packet that uses message compression in the QNAME and two pointers that point to each other (circular buffer).
http://www.FreeBSD.org/ports/portaudit/e72fd82b-fa01-11d9-bc08-0001020eed82.html
http://sourceforge.net/forum/forum.php?forum_id=482568