Public Date:
1340860: CVE-2016-4956 ntp: broadcast interleave (incomplete fix for CVE-2016-1548)

The MITRE CVE dictionary describes this issue as:

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.

Find out more about CVE-2016-4956 from the MITRE CVE dictionary dictionary and NIST NVD.

CVSS v2 metrics

NOTE: The following CVSS v2 metrics and score provided are preliminary and subject to review.

Base Score 2.6
Base Metrics AV:N/AC:H/Au:N/C:N/I:N/A:P
Access Vector Network
Access Complexity High
Authentication None
Confidentiality Impact None
Integrity Impact None
Availability Impact Partial

Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 7 ntp Will not fix
Red Hat Enterprise Linux 6 ntp Will not fix
Red Hat Enterprise Linux 5 ntp Will not fix


This issue was discovered by Miroslav Lichvar (Red Hat).


Do not use NTP's broadcast mode in the clients by not configuring the "broadcastclient" directive in the ntp.conf file.

External References

Last Modified

CVE description copyright © 2017, The MITRE Corporation