How severe is CVE-2016-5117?

CVE-2016-5117 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2016-5117 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-5117?

CVE-2016-5117 affects Openntpd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-5117?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2016-5117 published?

CVE-2016-5117 was published on 2017-01-31 and last updated on 2026-06-17.

CVE-2016-5117

CVE-2016-5117 is a medium-severity vulnerability in Openntpd with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-254.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-254
Affected product: Openntpd
Published: 2017-01-31
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2016-5117?: 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.
How severe is CVE-2016-5117?: CVE-2016-5117 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2016-5117 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-5117?: CVE-2016-5117 affects Openntpd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-5117?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-5117 published?: CVE-2016-5117 was published on 2017-01-31 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:openntpd:openntpd:*:*:*:*:*:*:*:*

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