CVE-2016-5117: Openntpd

Medium severity, CVSS 5.9. EPSS: 0.7% chance of exploitation in the next 30 days.

OpenNTPD before 6.0p1 does not validate the CN for HTTPS constraint requests, which allows remote attackers to bypass the man-in-the-middle mitigations via a crafted timestamp constraint with a valid certificate.

Affected products

• Openntpd Openntpd: up to and including 6.0

Published 2017-01-31. Last modified 2026-06-17.