CVE-2026-18321
Received Received - Intake

Buffer Overflow in NTPsec Zyfer Refclock

Publication date: 2026-07-31

Last updated on: 2026-07-31

Assigner: GitLab Inc.

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

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Meta Information

Published
2026-07-31
Last Modified
2026-07-31
Generated
2026-08-01
AI Q&A
2026-07-31
EPSS Evaluated
N/A
NVD
CVE-2026-18321
EUVD
EUVD-2026-51593

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-120 The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

Attack-Flow Graph

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Executive Summary

This vulnerability is a buffer overflow in NTPsec's Zyfer refclock component. It allows a local attacker to crash the ntpd service by exploiting this flaw.

Impact Analysis

The impact includes denial of service as the ntpd service crashes. Since it requires local access, the risk is limited to users with direct system access.

Compliance Impact

This vulnerability is a local buffer overflow in NTPsec's Zyfer refclock that crashes ntpd. It does not directly impact data confidentiality or integrity but may cause service disruption. Compliance impact depends on system criticality and availability requirements rather than direct data exposure.

Mitigation Strategies

Update NTPsec to the latest version to patch the buffer overflow in the Zyfer refclock. Disable the Zyfer refclock if not needed. Monitor ntpd logs for crashes or unusual activity.

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