PatchSiren

PatchSiren cyber security CVE debrief

CVE-2016-7433 Ntp CVE debrief

CVE-2016-7433 affects NTP versions before 4.2.8p9. The issue is described as an error in the initial synchronization calculations, specifically a root distance calculation that did not include peer dispersion. NVD rates the impact as medium severity with a low availability effect and no confidentiality or integrity impact in the published CVSS vector. The safest response is to upgrade to a fixed NTP release and validate any fleet-specific advisories or package updates tied to your platform.

Vendor
Ntp
Product
CVE-2016-7433
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-13
Original CVE updated
2026-05-13
Advisory published
2017-01-13
Advisory updated
2026-05-13

Who should care

System administrators, platform owners, and embedded or appliance teams running ntpd/NTP before 4.2.8p9 should care, especially where accurate time sync affects authentication, logging, monitoring, or distributed services.

Technical summary

The published vulnerability description says NTP before 4.2.8p9 did not properly perform initial sync calculations because the root distance calculation omitted peer dispersion. The NVD CPE criteria mark ntp versions up to 4.2.8 as vulnerable, and the CVSS vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L. The source corpus does not provide a detailed exploit narrative, so the defensible takeaway is a remotely reachable logic flaw that can affect time-sync availability or reliability rather than data confidentiality or integrity.

Defensive priority

Medium. Patch promptly because time services are foundational and the affected versions are publicly identified, but the published severity suggests limited direct impact compared with high-severity remote code execution issues.

Recommended defensive actions

  • Upgrade NTP to 4.2.8p9 or a later fixed release referenced by your vendor.
  • Check vendor packaging and advisories for your operating system or appliance, since multiple ecosystem advisories reference this CVE.
  • Review systems that depend on accurate time for authentication, certificates, logging, or distributed coordination.
  • If immediate upgrading is not possible, follow the vendor guidance referenced in the NTP security notice and issue tracker entries.
  • Verify deployed NTP versions against the vulnerable range identified in the NVD CPE criteria.

Evidence notes

The CVE description in the supplied corpus states that NTP before 4.2.8p9 improperly performed initial sync calculations due to a root distance that did not include peer dispersion. The NVD metadata lists affected NTP CPE criteria up to 4.2.8 and assigns CVSS v3.0 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L. The source references include the NTP release notes, NTP bug/mitigation page, and multiple vendor advisories, supporting the remediation guidance to upgrade and consult platform-specific notices.

Official resources

Publicly disclosed through standard CVE/NVD publication channels; the provided corpus does not indicate KEV inclusion or active exploit campaign use.