# CVE-2016-7429: NTP Project ntp denial of service in interface selection

Source: https://junglewise.ai/threats/cve-2016-7429-ntp-project-ntp-denial-of-service-in-interface-selection  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2017-01-13. Updated: 2026-05-13  
License: CC BY 4.0 with a link back

CVE-2016-7429 · Severity: low · CVSS 3.7 · Published 2017-01-13

A vulnerability in the Network Time Protocol (NTP) software can allow a remote attacker to disrupt time synchronization on servers with multiple network interfaces. By sending specially crafted responses, an attacker can prevent a system from communicating with its legitimate time sources. This can lead to inaccurate system clocks, which may impact time-sensitive operations, logging, and security protocols.

Technologies: [Ntp](https://junglewise.ai/threats/technologies/ntp). Vendors: [Ntp](https://junglewise.ai/threats/vendors/ntp).

## Quick answers

**Is CVE-2016-7429 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2016-7429 being exploited in the wild.

**How severe is CVE-2016-7429?** Low severity, with a CVSS score of 3.7, published 13 January 2017.

**Which products and versions are affected?** NTP Project ntp before 4.2.8p9; Red Hat Enterprise Linux 6, 7.

**Is there a fix for CVE-2016-7429?** A patch was published on 2017-02-06: Red Hat issued security updates RHSA-2017:0252 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2016-7429 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2016-7429?** Check whether you run Ntp. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A flaw exists in ntpd's handling of server responses on hosts configured with multiple network interfaces. When a response is received from a source, NTP incorrectly updates the peer structure to the interface on which the response was received. A remote attacker can exploit this by sending a spoofed response for a legitimate source to an interface that the source does not actually use. This causes ntpd to fail to synchronize with the legitimate source, resulting in a denial of service. The vulnerability is addressed in NTP version 4.2.8p9.

## Affected products

- NTP Project ntp before 4.2.8p9
- Red Hat Enterprise Linux 6, 7

## Timeline

- 2016-11-21: advisory: NTP Project release notes for 4.2.8p9
- 2017-01-13: disclosed: NVD publication date
- 2017-02-06: patched: Red Hat issued security updates RHSA-2017:0252

## References

- [http://nwtime.org/ntp428p9_release/](http://nwtime.org/ntp428p9_release/)
- [http://rhn.redhat.com/errata/RHSA-2017-0252.html](http://rhn.redhat.com/errata/RHSA-2017-0252.html)
- [http://support.ntp.org/bin/view/Main/NtpBug3072](http://support.ntp.org/bin/view/Main/NtpBug3072)
- [http://support.ntp.org/bin/view/Main/SecurityNotice](http://support.ntp.org/bin/view/Main/SecurityNotice)
- [http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html](http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html)
- [http://www.securityfocus.com/bid/94453](http://www.securityfocus.com/bid/94453)
- [http://www.securitytracker.com/id/1037354](http://www.securitytracker.com/id/1037354)

## Related threats

- [NTP ntpq protocol replay attack vulnerability](https://junglewise.ai/threats/cve-2015-8140-ntp-ntpq-protocol-replay-attack-vulnerability)
- [NTP ntpq origin timestamp leak and peer impersonation](https://junglewise.ai/threats/cve-2015-8139-ntp-ntpq-origin-timestamp-leak-and-peer-impersonation)
- [NTP and NTPsec reference clock impersonation vulnerability](https://junglewise.ai/threats/cve-2016-1551-ntp-and-ntpsec-reference-clock-impersonation-vulnerability)
- [NTP Project ntpd denial of service via large UDP packet on Windows](https://junglewise.ai/threats/cve-2016-9312-ntp-project-ntpd-denial-of-service-via-large-udp-packet-on-windows)
- [NTP Project ntpd denial of service in trap service](https://junglewise.ai/threats/cve-2016-9311-ntp-project-ntpd-denial-of-service-in-trap-service)