Is CVE-2016-2517 in the CISA KEV catalog?

No. CVE-2016-2517 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-2517?

CVE-2016-2517 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2016-2517?

CVE-2016-2517 has an EPSS score of 8.82% (95th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-2517?

Upgrade ntp on debian 11 to 1:4.2.8p7+dfsg-1 or later.

CVE & CISA-KEV Catalog

CVE-2016-2517

MEDIUMEPSS 95th pctl

5.3

CVSS v3

NVD

Description

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.

CWE-20Improper Input Validation

How to fix

Remediation Available

ntpDebian

Fixed in:1:4.2.8p7+dfsg-1CVE-2016-2517

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

8.82%probability of exploitation in 30 days

95thpercentile

High risk: more likely to be exploited than 95% of all known CVEs.

References

Vendor Advisory1

support.ntp.org

Third-Party Advisory3

Other references4

Related Vulnerabilities

Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2021-45105	Medium	5.9	100%	-	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2018-7600	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-3452	High	7.5	100%	KEV	Fix

Embed a live status badge for CVE-2016-2517

Markdown

[![CVE-2016-2517](https://tridentstack.com/cve/badge/CVE-2016-2517.svg)](https://tridentstack.com/cve/CVE-2016-2517)

HTML

<a href="https://tridentstack.com/cve/CVE-2016-2517"><img src="https://tridentstack.com/cve/badge/CVE-2016-2517.svg" alt="CVE-2016-2517"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.