CVE-2016-2517: Ntp

Medium severity, CVSS 5.3. EPSS: 8.8% chance of exploitation in the next 30 days.

NTP before 4.2.8p7 and 4.3.x before 4.3.92 allows remote attackers to cause a denial of service (prevent subsequent authentication) by leveraging knowledge of the controlkey or requestkey and sending a crafted packet to ntpd, which changes the value of trustedkey, controlkey, or requestkey. NOTE: this vulnerability exists because of a CVE-2016-2516 regression.

Affected products

• Ntp Ntp: up to and including 4.2.8; version 4.3.0 only; version 4.3.1 only; version 4.3.2 only; version 4.3.3 only; version 4.3.4 only; …

Published 2017-01-30. Last modified 2026-06-17.