CVE-2016-1551

LOWNVD 3.73.7—
EchelonGraph scoreMEDIUM confidence

Score 3.7 from GitHub Security Advisory (severity: LOW) published 2022-05-17. NVD baseline CVSS 3.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
3.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 3.7Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

ntpd in NTP 4.2.8p3 and NTPsec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 relies on the underlying operating system to protect it from requests that impersonate reference clocks. Because reference clocks are treated like other peers and stored in the same structure, any packet with a source ip address of a reference clock (127.127.1.1 for example) that reaches the receive() function will match that reference clock's peer record and will be treated as a trusted peer. Any system that lacks the typical martian packet filtering which would block these packets is in danger of having its time controlled by an attacker.

CVSS v3
3.7
EG Score
3.7(medium)
EG Risk
22(Track)
EG Risk 22/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity37% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
80.9%
KEV
Not listed

Published

January 27, 2017

Last Modified

May 13, 2026

References (14)

Data Freshness Timeline

(refreshed 10× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:14 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2016-1551?
CVE-2016-1551 is a low vulnerability published on January 27, 2017. ntpd in NTP 4.2.8p3 and NTPsec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 relies on the underlying operating system to protect it from requests that impersonate reference clocks. Because reference clocks are treated like other peers and stored in the same structure, any packet with a source ip…
When was CVE-2016-1551 disclosed?
CVE-2016-1551 was first published in the National Vulnerability Database on January 27, 2017, with the most recent update on May 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-1551 actively exploited?
CVE-2016-1551 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 80.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-1551?
CVE-2016-1551 has a CVSS v3 base score of 3.7 (NVD).
How do I remediate CVE-2016-1551?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-1551, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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