Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-11d8a5a213 advisory.

    Update to the latest upstream release, which has a security fix for CVE-2026-18321, and other bug fixes     and improvements.



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-80887c367d advisory.

    Update to the latest upstream release, which has a security fix for CVE-2026-18321, and other bug fixes     and improvements.



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd (CVE-2026-18321)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd (CVE-2026-18321)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
338395	Fedora 43 : ntpsec (2026-11d8a5a213)	Nessus	Fedora Local Security Checks	Local	medium
338394	Fedora 44 : ntpsec (2026-80887c367d)	Nessus	Fedora Local Security Checks	Local	medium
445581	Alpine: multiple ntpsec packages: security update to 1.2.5-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	medium
445581	Alpine: multiple ntpsec packages: security update to 1.2.5-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	medium
331480	Linux Distros Unpatched Vulnerability : CVE-2026-18321	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-18321

medium

Tenable Plugins

medium

medium

medium

medium

medium