CVE-2016-4953

Publication date 5 July 2016

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ntp	16.04 LTS xenial	Not affected
	15.10 wily	Ignored end of life
	14.04 LTS trusty	Not affected
	12.04 LTS precise	Not affected

Notes

mdeslaur

incomplete fix for CVE-2015-7979 and CVE-2016-1547 redhat's fix for CVE-2015-7979 doesn't introduce this CVE Ubuntu uses redhat's fix

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H