CVE-2016-7427 Ntp CVE debrief

Who should care

Administrators and operators running ntpd in broadcast mode, especially on systems that rely on time synchronization for infrastructure, monitoring, or distributed services. Security teams should care most where a time service outage or degraded synchronization would create operational risk.

Technical summary

The issue is tied to ntpd's broadcast mode replay-prevention functionality. The NVD record describes a condition where a crafted broadcast mode packet can cause the service to reject broadcast mode packets, resulting in a denial of service. NVD maps the weakness to CWE-400 (Uncontrolled Resource Consumption) and rates the attack as adjacent-network accessible with no privileges or user interaction required.

Defensive priority

Medium. The impact is limited to availability, but time synchronization failures can have broad operational effects in environments that depend on broadcast-mode NTP.

Recommended defensive actions

• Upgrade ntpd to 4.2.8p9 or later, as indicated by the vendor release references.
• Identify whether any systems use NTP broadcast mode and prioritize those hosts for patching.
• Review vendor advisories and mitigation notes linked in the CVE record before and during remediation.
• Monitor ntpd logs and service health for broadcast-mode packet rejection or synchronization disruption after mitigation.
• Validate that time-dependent infrastructure continues to synchronize correctly following the update.

Evidence notes

This debrief is based only on the supplied NVD/CVE record and its referenced advisory links. The record states that ntpd before 4.2.8p9 is affected, with vulnerable CPEs explicitly listed for 4.2.8p6, 4.2.8p7, and 4.2.8p8. The published date used here is the CVE publication timestamp provided in the corpus (2017-01-13); the later modified timestamp is not treated as the issue date. No direct content was fetched from the linked advisories, so details beyond the supplied descriptions are intentionally omitted.

Official resources