FreeBSD Security Advisory – The ntpd(8) daemon is prone to a stack-based buffer-overflow when it is configured to use the ‘autokey’ security model.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/78263/FreeBSD-SA-09-11.ntpd.txt
Source: https://packetstormsecurity.com/files/78263/FreeBSD-Security-Advisory-ntpd-Buffer-Overflow.html