# CVE-2015-7975: NTP nextvar function memory corruption denial of service

Source: https://junglewise.ai/threats/cve-2015-7975-ntp-nextvar-function-memory-corruption-denial-of-service  
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-2015-7975 · Severity: medium · CVSS 6.2 · Published 2017-01-30

A vulnerability exists in the Network Time Protocol (NTP) software, which is used to synchronize clocks across computer networks. An attacker can exploit this flaw to cause the NTP service to crash, leading to a denial of service. This can disrupt time-sensitive operations and network logging that rely on accurate time synchronization.

## Quick answers

**Is CVE-2015-7975 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2015-7975 being exploited in the wild.

**How severe is CVE-2015-7975?** Medium severity, with a CVSS score of 6.2, published 30 January 2017.

**Which products and versions are affected?** NTP Project ntp Before 4.2.8p6, 4.3.x before 4.3.90.

**Is there a fix for CVE-2015-7975?** 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-2015-7975 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2015-7975?** 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 memory buffer validation vulnerability (CWE-119) exists in the nextvar function of the NTP daemon (ntpd). The component fails to properly validate the length of input strings, leading to a potential buffer overflow or similar memory corruption when processing specific variables. An attacker with local access can exploit this to trigger an application crash, resulting in a denial of service. The issue is resolved in NTP versions 4.2.8p6 and 4.3.90.

## Affected products

- NTP Project ntp Before 4.2.8p6, 4.3.x before 4.3.90

## Timeline

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

## References

- [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)
- [http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00026.html](http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00026.html)
- [http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00042.html](http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00042.html)