View at Official ubuntu advisory, NVD, CVE.org · CVE detail
Freshness: upstream tracker timestamp is available; use API updated time as primary recency signal.
CVE-2016-4953 medium priority: Ubuntu including 1 source packages (ntp), 5 status rows across 5 suites (precise, trusty, upstream, wily, xenial): not-affected 3, ignored 1, needs-triage 1.
ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.