CVE-2016-9311 Ntp CVE debrief

Who should care

Administrators and security teams running NTP/ntpd, especially on systems where the trap service is enabled or where older NTP builds may still be in use.

Technical summary

The NVD record says ntpd in NTP before 4.2.8p9 is vulnerable when the trap service is enabled. A remotely sent crafted packet can cause ntpd to dereference a NULL pointer and crash, resulting in denial of service. The mapped weakness is CWE-476 (NULL Pointer Dereference).

Defensive priority

Medium: this is a remote availability impact issue, not a code-execution flaw, but it can still disrupt time synchronization on exposed or widely deployed NTP servers.

Recommended defensive actions

• Upgrade NTP/ntpd to 4.2.8p9 or later, using the vendor release notes and OS advisory guidance referenced by NVD.
• Check whether the trap service is enabled on affected hosts and disable it if it is not required.
• Review vendor advisories and security notices for your distribution or appliance build, including the NTP project notice and downstream vendor errata.
• Limit unnecessary network exposure to NTP services and monitor for unexpected ntpd restarts or crashes.
• Confirm patch status across all systems that ship ntpd, including third-party appliances and embedded distributions.

Evidence notes

The description, CVSS vector, and CWE come from the NVD record. The vendor and mitigation references include the NTP 4.2.8p9 release notes, the NTP security notice, and downstream advisories such as Red Hat, FreeBSD, Ubuntu, HPE, Blue Coat, and CERT/CC. The supplied record also lists the issue as affecting NTP before 4.2.8p9 when the trap service is enabled.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.