CVE-2009-3563

ntp < 4.2.4p8 and 4.2.5 - Denial of Service via MODE_PRIVATE Packet Spoofing

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2009-3563. PoCs published by todb, including Metasploit module auxiliary/dos/ntp/ntpd_reserved_dos.

AI-analyzed exploit summary This Metasploit module exploits a denial of service vulnerability in NTP.org's ntpd by sending a spoofed mode 7 packet, causing an infinite response loop between two vulnerable servers. The exploit is functional and leverages packet crafting to trigger the DoS condition.

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.

Exploits (1)

metasploit WORKING POC
by todb · rubypoc
https://github.com/rapid7/metasploit-framework/blob/master/modules/auxiliary/dos/ntp/ntpd_reserved_dos.rb

This Metasploit module exploits a denial of service vulnerability in NTP.org's ntpd by sending a spoofed mode 7 packet, causing an infinite response loop between two vulnerable servers. The exploit is functional and leverages packet crafting to trigger the DoS condition.

Classification
Working Poc 100%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: NTP.org ntpd (versions affected by CVE-2009-3563)
No auth needed
Prerequisites: Access to a vulnerable ntpd server · Ability to spoof packets from another vulnerable ntpd server
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (43)

Core 43
Core References
Patch, US Government Resource third-party-advisory
http://www.kb.cert.org/vuls/id/568372
Vendor Advisory vendor-advisory
https://rhn.redhat.com/errata/RHSA-2009-1651.html
Third Party Advisory, US Government Resource
http://www.kb.cert.org/vuls/id/MAPG-7X7V6J
Third Party Advisory, US Government Resource
http://www.kb.cert.org/vuls/id/MAPG-7X7VD7
Third Party Advisory third-party-advisory
http://secunia.com/advisories/38832
Third Party Advisory third-party-advisory
http://secunia.com/advisories/38794
Third Party Advisory third-party-advisory
http://secunia.com/advisories/38764
Third Party Advisory third-party-advisory
http://secunia.com/advisories/39593
Third Party Advisory vdb-entry
http://www.vupen.com/english/advisories/2010/0993
Third Party Advisory third-party-advisory
http://secunia.com/advisories/37922
Third Party Advisory third-party-advisory
http://secunia.com/advisories/38834
Third Party Advisory, VDB Entry vdb-entry
http://securitytracker.com/id?1023298
Third Party Advisory third-party-advisory
http://secunia.com/advisories/37629
Vendor Advisory vendor-advisory
https://rhn.redhat.com/errata/RHSA-2010-0095.html
Third Party Advisory vdb-entry
http://www.vupen.com/english/advisories/2010/0510
Vendor Advisory vendor-advisory
https://rhn.redhat.com/errata/RHSA-2009-1648.html
Third Party Advisory vdb-entry
http://www.vupen.com/english/advisories/2010/0528
Third Party Advisory, US Government Resource third-party-advisory
https://www.kb.cert.org/vuls/id/417980

Scores

EPSS 0.8111
EPSS Percentile 99.2%

Details

Status published
Products (21)
ntp/ntp 4.0.72
ntp/ntp 4.0.73
ntp/ntp 4.0.90
ntp/ntp 4.0.91
ntp/ntp 4.0.92
ntp/ntp 4.0.93
ntp/ntp 4.0.94
ntp/ntp 4.0.95
ntp/ntp 4.0.96
ntp/ntp 4.0.97
... and 11 more
Published Dec 09, 2009
Tracked Since Feb 18, 2026