CVE-2016-1547

Publication date 29 April 2016

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

An off-path attacker can cause a preemptible client association to be demobilized in NTP 4.2.8p4 and earlier and NTPSec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 by sending a crypto NAK packet to a victim client with a spoofed source address of an existing associated peer. This is true even if authentication is enabled.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ntp	17.04 zesty	Not affected
	16.10 yakkety	Not affected
	16.04 LTS xenial	Fixed 1:4.2.8p4+dfsg-3ubuntu5.3
	15.10 wily	Ignored end of life
	14.04 LTS trusty	Fixed 1:4.2.6.p5+dfsg-3ubuntu2.14.04.10
	12.04 LTS precise	Fixed 1:4.2.6.p3+dfsg-1ubuntu3.11

Notes

mdeslaur

fedora patch for CVE-2015-7979 also covers this CVE

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
ntp	Upstream: http://bk1.ntp.org/ntp-stable/?PAGE=patch&REV=56ca82fbM-SM7MAKmqf27DRTW1r6KQ Upstream: http://bk1.ntp.org/ntp-stable/?PAGE=patch&REV=5719625aNcSIWNqKMs4tNUS8r4xp-Q Vendor: http://pkgs.fedoraproject.org/cgit/rpms/ntp.git/tree/ntp-4.2.6p5-cve-2015-7979.patch

Severity score breakdown

Parameter	Value
Base score	5.3 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	Low
Vector	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

Related Ubuntu Security Notices (USN)

USN-3096-1
NTP vulnerabilities
5 October 2016