CVE-2016-2517

Publication date 30 January 2017

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

NTP before 4.2.8p7 and 4.3.x before 4.3.92 allows remote attackers to cause a denial of service (prevent subsequent authentication) by leveraging knowledge of the controlkey or requestkey and sending a crafted packet to ntpd, which changes the value of trustedkey, controlkey, or requestkey. NOTE: this vulnerability exists because of a CVE-2016-2516 regression.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ntp	16.04 LTS xenial	Ignored
	15.10 wily	Ignored
	14.04 LTS trusty	Ignored
	12.04 LTS precise	Ignored

Notes

mdeslaur

isn't really considered a security issue since remote user can do other equivalent configuration changes, ignoring.

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=56c78c41-oKNCUhyU5kKQCxLjnp0Fw Upstream: http://bk1.ntp.org/ntp-stable/?PAGE=patch&REV=56c977bdf6CLtHiqg1_rd2II7E0dqA

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.3 · Medium

Base metrics

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

Scores

Parameter	Value
Base score	5.3 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H