ASA-2019-00269 – FreeBSD: Authenticated denial of service in ntpd

A crafted malicious authenticated mode 6 packet from a permitted network address can trigger a NULL pointer dereference. Note for this attack to work, the sending system must be on an address from which the target ntpd(8) accepts mode 6 packets, and must use a private key that is specifically listed as being used for mode 6 authorization.