CVE-2016-4953

7.5 HIGH 17% exploit odds Fix listed Auth & access

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 17.2% chance of exploitation in the next 30 days (EPSS). Higher than most.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2016-07-05 01:59 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 00:48 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 17.2% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2016-07-05 01:59 UTC
Last modified: 2026-06-17 00:48 UTC
Exploit probability: 17.2% · EPSS, next 30 days
Weakness: CWE-287 · Improper authentication
Record status: Modified

Affected

Ntp < 4.2.8
Ntp < 4.3.93
Ntp 4.2.8
Oracle Solaris 10
Oracle Solaris 11.3
Suse Manager 2.1
Suse Manager Proxy 2.1
Suse Openstack Cloud 5

Attack profile CVSS 3.1 · 7.5

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2016-4953.md and follow it. Check whether this project is affected by CVE-2016-4953. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record