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Vulnerability record · CVE-2016-4956 · published 5 July 2016

CVE-2016-4956: Ntp vulnerability

Ntp · Ntp

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (interleaved-mode transition and time change) via a spoofed broadcast packet. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-1548.

5.3 CVSS 3.1 Medium EPSS 16% · top 3.1%
5.3CVSS 3.1 base score, v2 5.0
16%EPSS exploitation probability, 30 days
NoNot in CISA KEV
10Affected product versions listed by NVD
66References
17 Jun 2026Last modified by NVD

Description

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (interleaved-mode transition and time change) via a spoofed broadcast packet. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-1548.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

10 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://bugs.ntp.org/3042 Issue TrackingVendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00018.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00023.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00024.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00028.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00040.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00026.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00042.html
http://packetstormsecurity.com/files/137321/Slackware-Security-Advisory-ntp-Updates.html
http://support.ntp.org/bin/view/Main/NtpBug3042 Vendor Advisory
http://support.ntp.org/bin/view/Main/SecurityNotice Release NotesVendor Advisory
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160603-ntpd
http://www.kb.cert.org/vuls/id/321640 Third Party AdvisoryUS Government Resource
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html Third Party Advisory
http://www.securityfocus.com/archive/1/538599/100/0/threaded
http://www.securityfocus.com/archive/1/538600/100/0/threaded
http://www.securityfocus.com/archive/1/540683/100/0/threaded
http://www.securityfocus.com/archive/1/archive/1/538599/100/0/threaded
http://www.securityfocus.com/archive/1/archive/1/538600/100/0/threaded
http://www.securityfocus.com/archive/1/archive/1/540683/100/0/threaded
http://www.securityfocus.com/bid/91009 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1036037 Third Party AdvisoryVDB Entry
http://www.ubuntu.com/usn/USN-3096-1
https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf Third Party Advisory
https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03757en_us Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3EYJQHJZ2KTVQ7ICEFHXTL
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORAMN3Q7TVJ54MBYF75XCJO
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WNWGCQLW2VY72NIUYMJOCAK
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:24.ntp.asc Third Party Advisory
https://security.gentoo.org/glsa/201607-15 Third Party Advisory
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-11
https://www.kb.cert.org/vuls/id/321640
http://bugs.ntp.org/3042 Issue TrackingVendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00018.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00023.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00024.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00028.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00040.html Mailing ListThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2016-4956), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.