{"id":"CVE-2016-1547","url":"https://www.cyber-defence.io/tools/cve/CVE-2016-1547","generatedAt":"2026-10-27T17:58:22.266Z","title":"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…","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.","published":"2017-01-06T21:59:00.000Z","lastModified":"2026-06-17T00:42:09.000Z","status":"Modified","sourceIdentifier":"cret@cert.org","cvss":{"version":"3.0","score":5.3,"severity":"MEDIUM","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"cwe":["CWE-20"],"affected":["ntp/ntp"],"epss":{"score":0.05068,"percentile":0.92267,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (5.07%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"http://rhn.redhat.com/errata/RHSA-2016-1552.html","source":"cret@cert.org"},{"url":"http://www.debian.org/security/2016/dsa-3629","source":"cret@cert.org"},{"url":"http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html","source":"cret@cert.org"},{"url":"http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html","source":"cret@cert.org"},{"url":"http://www.securityfocus.com/bid/88276","source":"cret@cert.org"},{"url":"http://www.securitytracker.com/id/1035705","source":"cret@cert.org"},{"url":"http://www.talosintelligence.com/reports/TALOS-2016-0081/","tags":["Mitigation","Technical Description","Third Party Advisory"],"source":"cret@cert.org"},{"url":"https://access.redhat.com/errata/RHSA-2016:1141","source":"cret@cert.org"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf","source":"cret@cert.org"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf","source":"cret@cert.org"},{"url":"https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc","source":"cret@cert.org"},{"url":"https://security.gentoo.org/glsa/201607-15","source":"cret@cert.org"},{"url":"https://security.netapp.com/advisory/ntap-20171004-0002/","source":"cret@cert.org"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11","source":"cret@cert.org"},{"url":"https://www.arista.com/en/support/advisories-notices/security-advisories/1332-security-advisory-19","source":"cret@cert.org"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1552.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.debian.org/security/2016/dsa-3629","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/88276","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securitytracker.com/id/1035705","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.talosintelligence.com/reports/TALOS-2016-0081/","tags":["Mitigation","Technical Description","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2016:1141","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.gentoo.org/glsa/201607-15","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20171004-0002/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.arista.com/en/support/advisories-notices/security-advisories/1332-security-advisory-19","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2016-1547","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}