# CVE-2015-7978: NTP Project NTP denial of service via stack exhaustion in ntpdc

Source: https://junglewise.ai/threats/cve-2015-7978-ntp-project-ntp-denial-of-service-via-stack-exhaustion-in-ntpdc  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2017-01-30. Updated: 2026-05-13  
License: CC BY 4.0 with a link back

CVE-2015-7978 · Severity: high · CVSS 7.5 · Published 2017-01-30

A vulnerability in the Network Time Protocol (NTP) service, which synchronizes clocks across computer networks, could allow an attacker to crash the service. By sending a specific command, a remote attacker can cause the system to exhaust its memory resources, leading to a denial of service. This can disrupt time-sensitive operations and security protocols that rely on accurate system clocks.

## Quick answers

**Is CVE-2015-7978 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2015-7978 being exploited in the wild.

**How severe is CVE-2015-7978?** High severity, with a CVSS score of 7.5, published 30 January 2017.

**Which products and versions are affected?** NTP Project NTP 4.2.8p6 and earlier, 4.3.0 through 4.3.89.

**Is there a fix for CVE-2015-7978?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2015-7978 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2015-7978?** 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 stack exhaustion vulnerability exists in the NTP daemon (ntpd) when processing 'ntpdc relist' commands. The flaw is rooted in the recursive traversal of the restriction list; an attacker can trigger this recursion remotely without authentication. Successful exploitation leads to a crash of the ntpd process, resulting in a denial of service. This issue affects NTP versions prior to 4.2.8p6 and the 4.3 development branch prior to 4.3.90. Users are advised to upgrade to NTP 4.2.8p6 or later.

## Affected products

- NTP Project NTP 4.2.8p6 and earlier, 4.3.0 through 4.3.89

## Timeline

- 2016-01-27: advisory: Cisco security advisory published
- 2017-01-30: disclosed: NVD publication date

## References

- [http://lists.fedoraproject.org/pipermail/package-announce/2016-February/177507.html](http://lists.fedoraproject.org/pipermail/package-announce/2016-February/177507.html)
- [http://lists.fedoraproject.org/pipermail/package-announce/2016-January/176434.html](http://lists.fedoraproject.org/pipermail/package-announce/2016-January/176434.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00059.html](http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00059.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00060.html](http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00060.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00020.html](http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00020.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00038.html](http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00038.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00048.html](http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00048.html)