# CVE-2016-7434: NTP Project NTP denial of service in read_mru_list

Source: https://junglewise.ai/threats/cve-2016-7434-ntp-project-ntp-denial-of-service-in-read-mru-list  
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-2016-7434 · Severity: high · CVSS 7.5 · Published 2017-01-13

A vulnerability in the Network Time Protocol (NTP) service, which is used to synchronize clocks across computer systems, could allow a remote attacker to crash the service. By sending a specially crafted request, an attacker can cause the NTP daemon to stop responding, potentially disrupting time-sensitive operations and logging across the network. This issue affects various versions of NTP prior to 4.2.8p9.

## Quick answers

**Is CVE-2016-7434 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2016-7434 being exploited in the wild.

**How severe is CVE-2016-7434?** High severity, with a CVSS score of 7.5, published 13 January 2017.

**Which products and versions are affected?** NTP Project NTP before 4.2.8p9.

**Is there a fix for CVE-2016-7434?** A patch was published on 2016-11-21: Fixed in NTP 4.2.8p9 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2016-7434 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2016-7434?** Check whether anything you run is named in the advisory. 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 denial of service vulnerability exists in the NTP daemon's read_mru_list function due to improper input validation of incoming packets. A remote, unauthenticated attacker can exploit this by sending a specially crafted 'mrulist' query to the NTP server. This triggers a crash in the ntpd process, leading to a complete loss of availability for the time synchronization service. The vulnerability is addressed in NTP version 4.2.8p9.

## Affected products

- NTP Project NTP before 4.2.8p9

## Timeline

- 2016-11-21: disclosed: Initial public disclosure via NTP project bug 3082
- 2016-11-21: patched: Fixed in NTP 4.2.8p9
- 2017-01-13: advisory: NVD publication date

## References

- [http://nwtime.org/ntp428p9_release/](http://nwtime.org/ntp428p9_release/)
- [http://support.ntp.org/bin/view/Main/NtpBug3082](http://support.ntp.org/bin/view/Main/NtpBug3082)
- [http://support.ntp.org/bin/view/Main/SecurityNotice](http://support.ntp.org/bin/view/Main/SecurityNotice)
- [http://www.securityfocus.com/bid/94448](http://www.securityfocus.com/bid/94448)
- [http://www.securitytracker.com/id/1037354](http://www.securitytracker.com/id/1037354)
- [https://bto.bluecoat.com/security-advisory/sa139](https://bto.bluecoat.com/security-advisory/sa139)
- [https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03706en_us](https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03706en_us)