CVE-2016-1547

Severity: medium (CVSS 5.3 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 5.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2017-01-06 · updated 2026-06-17
Weakness: CWE-20

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.

Affected products

NTP: through 4.2.8

References

http://rhn.redhat.com/errata/RHSA-2016-1552.html
http://www.debian.org/security/2016/dsa-3629
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.securityfocus.com/bid/88276
http://www.securitytracker.com/id/1035705
http://www.talosintelligence.com/reports/TALOS-2016-0081/
https://access.redhat.com/errata/RHSA-2016:1141
https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf
https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc
https://security.gentoo.org/glsa/201607-15

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