{"cve":"CVE-2016-1551","nvd":{"published":"2017-01-27T17:59:00.227","modified":"2026-06-17T00:42:09.300","status":"Modified","description":"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_v4":null,"cvss_v3":{"version":"3.0","vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7},"cwes":["CWE-254"],"references":["http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html","http://www.securityfocus.com/bid/88219","http://www.securitytracker.com/id/1035705","http://www.talosintelligence.com/reports/TALOS-2016-0132/","https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc"],"products":["ntp:ntp","ntpsec:ntpsec"],"source":"nvd","synced_at":"2026-10-19T20:41:25.729257544+00:00"},"epss":{"cve":"CVE-2016-1551","score":0.02233,"percentile":0.82771,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}