CVE-2016-4953
No exploitation reported by the sources we read.
- Published2016-07-05
- Fixed in4.3.93 · 4.2.8
- WeaknessCWE-287
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
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.
Timeline
dates in UTC- 2016-07-0501:59CVE publishedNVD
- 2026-10-2319:23EPSS crossed 10 %FIRST EPSS
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2016-4953?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-4953?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 4.3 | ≥ 4.3.0, < 4.3.93 | 4.3.93 | NVD |
| 4.2 | ≥ 4.2.0, < 4.2.8 | 4.2.8 | NVD |
| 4.2 | = 4.2.8 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 10.x | = 10 | no fix published | NVD |
| 11.3 | = 11.3 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 11.x | = 11 | no fix published | NVD |
| 12.x | = 12 | no fix published | NVD |
9 more products in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
Siemens TIM 4R-IE Devices
SIPLUS NET TIM 4R-IE (6AG1800-4BA00-7AA0) · SIPLUS NET TIM 4R-IE DNP3 (6AG1803-4BA00-7AA0) · TIM 4R-IE (6NH7800-4BA00) · +1 more
Fix
- Update Ntp to 4.3.93 · 4.2.8
- Workaround from the vendor CISA ICSA-21-103-11 · 4 productsDeactivate NTP-based time syncronization of the device, if enabled. The feature is disabled by default.
- Workaround from the vendor CISA ICSA-21-103-11 · 4 productsConfigure an additional firewall to prevent communication to the port udp/123 of an affected device.
- No fix planned, says the vendor CISA ICSA-21-103-11 · 4 productsCurrently no fix is planned
Advisories and patches
- bugs.ntp.orgVendor Advisory
- support.ntp.orgPatch · Vendor Advisory
- support.ntp.orgVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- NVDCVSS 3.17.5read 2026-10-23
- NVDCVSS 2.05read 2026-10-23
- NVDweakness (CWE)CWE-287read 2026-10-23
- FIRST EPSSEPSS score17.2 %read 2026-10-23
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2016-07-05
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2016-4953?
Is CVE-2016-4953 actively exploited?
What is the CVSS score for CVE-2016-4953?
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.