{"id":"CVE-2016-2517","url":"https://www.cyber-defence.io/tools/cve/CVE-2016-2517","generatedAt":"2026-10-27T23:20:08.084Z","title":"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…","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.","published":"2017-01-30T21:59:01.000Z","lastModified":"2026-06-17T00:44:12.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.0","score":5.3,"severity":"MEDIUM","vector":"CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-20"],"affected":["ntp/ntp"],"epss":{"score":0.08823,"percentile":0.95155,"date":"2026-10-26","history":[{"date":"2026-09-21","score":0.07505,"percentile":0.94303},{"date":"2026-09-22","score":0.08823,"percentile":0.94951}]},"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 (8.82%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"http://support.ntp.org/bin/view/Main/NtpBug3010","tags":["Vendor Advisory"],"source":"cve@mitre.org"},{"url":"http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"http://www.securityfocus.com/bid/88189","tags":["Third Party Advisory","VDB Entry"],"source":"cve@mitre.org"},{"url":"http://www.securitytracker.com/id/1035705","source":"cve@mitre.org"},{"url":"https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc","source":"cve@mitre.org"},{"url":"https://security.gentoo.org/glsa/201607-15","source":"cve@mitre.org"},{"url":"https://security.netapp.com/advisory/ntap-20171004-0002/","source":"cve@mitre.org"},{"url":"https://www.kb.cert.org/vuls/id/718152","tags":["Third Party Advisory","US Government Resource"],"source":"cve@mitre.org"},{"url":"http://support.ntp.org/bin/view/Main/NtpBug3010","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/88189","tags":["Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securitytracker.com/id/1035705","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://www.kb.cert.org/vuls/id/718152","tags":["Third Party Advisory","US Government Resource"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2016-2517","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."}