A vulnerability has been found and corrected in ntp:
Robin Park and Dmitri Vinokurov discovered a flaw in the way ntpd
handled certain malformed NTP packets. ntpd logged information about
all such packets and replied with an NTP packet that was treated as
malformed when received by another ntpd. A remote attacker could use
this flaw to create an NTP packet reply loop between two ntpd servers
via a malformed packet with a spoofed source IP address and port,
causing ntpd on those servers to use excessive amounts of CPU time
and fill disk space with log messages (CVE-2009-3563).
This update provides a solution to this vulnerability.