HOMEVULNERABILITIESCVE-2016-2517
MEDIUM

CVE-2016-2517

CWE-20Published: January 30, 2017· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2016-2517 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 5.3.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityHigh
Privileges Req.Low
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

Affected Vendors & Products

ntp1 product(s)
ntp
Source: NVD CPE · 93 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttp://support.ntp.org/bin/view/Main/NtpBug3010
ADVISORYhttp://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
ADVISORYhttp://www.securityfocus.com/bid/88189
ADVISORYhttps://www.kb.cert.org/vuls/id/718152
ADVISORYhttp://support.ntp.org/bin/view/Main/NtpBug3010
ADVISORYhttp://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
ADVISORYhttp://www.securityfocus.com/bid/88189
ADVISORYhttps://www.kb.cert.org/vuls/id/718152

All References (16)

→
http://support.ntp.org/bin/view/Main/NtpBug3010Vendor Advisory
→
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.htmlThird Party Advisory
→
http://www.securityfocus.com/bid/88189Third Party Advisory · VDB Entry
→
http://www.securitytracker.com/id/1035705
→
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc
→
https://security.gentoo.org/glsa/201607-15
→
https://security.netapp.com/advisory/ntap-20171004-0002/
→
https://www.kb.cert.org/vuls/id/718152Third Party Advisory · US Government Resource
→
http://support.ntp.org/bin/view/Main/NtpBug3010Vendor Advisory
→
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.htmlThird Party Advisory
→
http://www.securityfocus.com/bid/88189Third Party Advisory · VDB Entry
→
http://www.securitytracker.com/id/1035705
→
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc
→
https://security.gentoo.org/glsa/201607-15
→
https://security.netapp.com/advisory/ntap-20171004-0002/

Quick Facts

CVE IDCVE-2016-2517
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-20
CISA KEVNo
Affected1 vendor(s)
PublishedJan 30, 2017

Related CVEs (CWE-20)

CVE-2017-16845
10.0
CVE-2020-12388
10.0
CVE-2017-7213
10.0
CVE-2017-10918
10.0
CVE-2020-6962
10.0
CVE-2020-12389
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2016-2517 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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