Ubuntu Security Notice 867-1 – Robin Park and Dmitri Vinokurov discovered a logic error in ntpd. A remote attacker could send a crafted NTP mode 7 packet with a spoofed IP address of an affected server and cause a denial of service via CPU and disk resource consumption.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/83609/USN-867-1.txt
Source: https://packetstormsecurity.com/files/83609/Ubuntu-Security-Notice-867-1.html