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Vulnerability record · CVE-2016-4954 · published 5 July 2016

CVE-2016-4954: Ntp race condition vulnerability

Ntp · Ntp

The process_packet function in ntp_proto.c in ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (peer-variable modification) by sending spoofed packets from many source IP addresses in a certain scenario, as demonstrated by triggering an incorrect leap indication.

7.5 CVSS 3.1 High EPSS 13% · top 3.8% CWE-362 · Race condition
7.5CVSS 3.1 base score, v2 5.0
13%EPSS exploitation probability, 30 days
NoNot in CISA KEV
12Affected product versions listed by NVD
70References
17 Jun 2026Last modified by NVD

Description

The process_packet function in ntp_proto.c in ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (peer-variable modification) by sending spoofed packets from many source IP addresses in a certain scenario, as demonstrated by triggering an incorrect leap indication.

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

Affected products

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

References

LinkTags
http://bugs.ntp.org/3044 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://packetstormsecurity.com/files/137322/FreeBSD-Security-Advisory-FreeBSD-SA-16-24.ntp.html
http://support.ntp.org/bin/view/Main/NtpBug3044 PatchVendor Advisory
http://support.ntp.org/bin/view/Main/SecurityNotice Vendor 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.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://cert-portal.siemens.com/productcert/pdf/ssa-497656.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-21-103-11 Third Party AdvisoryUS Government Resource
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-11
https://www.kb.cert.org/vuls/id/321640
http://bugs.ntp.org/3044 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

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Source: NIST National Vulnerability Database (record CVE-2016-4954), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.