HOMEVULNERABILITIESCVE-2016-4953
HIGH

CVE-2016-4953

CWE-287Published: July 5, 2016· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.

NVD Source

Technical Analysis

CVE-2016-4953 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

From a weakness classification perspective (CWE-287): Authentication bypass vulnerabilities allow attackers to access protected resources without valid credentials.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

ntp1 product(s)
ntp
openSUSE2 product(s)
leapopensuse
Oracle1 product(s)
solaris
siemens6 product(s)
simatic net cp 443-1 opc ua firmwaresimatic net cp 443-1 opc uatim 4r-ie firmwaretim 4r-ietim 4r-ie dnp3 firmwaretim 4r-ie dnp3
SUSE5 product(s)
managermanager proxyopenstack cloudlinux enterprise desktoplinux enterprise server
Source: NVD CPE · 18 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
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Official Patches & Advisories

All References (64)

Quick Facts

CVE IDCVE-2016-4953
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-287
CISA KEVNo
Affected5 vendor(s)
PublishedJul 5, 2016

Related CVEs (CWE-287)

Recommended Actions

  • Apply vendor patches immediately
  • Monitor CVE-2016-4953 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.