Quick answers
- Is CVE-2026-18321 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-18321 being exploited in the wild.
- How severe is CVE-2026-18321?
- Medium severity, with a CVSS score of 4.7, published 31 July 2026.
- Which products and versions are affected?
- Ntpsec < 1.2.5.
- Is there a fix for CVE-2026-18321?
- 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-2026-18321 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-18321?
- Check whether you run Ntpsec at an affected version. 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 classic buffer overflow (CWE-120) exists in the Zyfer reference clock (refclock) driver within NTPsec. The vulnerability is caused by a buffer copy operation that does not properly check the size of the input data. A local attacker with low privileges can exploit this flaw to trigger a crash of the ntpd daemon. The attack requires specific conditions (high complexity) but results in a partial impact on system availability. The issue is addressed in NTPsec version 1.2.5.
Affected products
- NTPsec ntpsec < 1.2.5
Timeline
- 2026-07-31: disclosed
- 2026-07-31: advisory