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Vulnerability record · CVE-2009-3563 · published 9 December 2009

CVE-2009-3563: Ntp vulnerability

Ntp · Ntp

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.

6.4 CVSS 2.0 Medium EPSS 32% · top 1.7%
6.4CVSS 2.0 base score
32%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
86References
16 Jun 2026Last modified by NVD

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.

AV:N/AC:L/Au:N/C:N/I:P/A:P

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2010-005.txt.asc
http://aix.software.ibm.com/aix/efixes/security/xntpd_advisory.asc
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=560074
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10673
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10691
http://lists.vmware.com/pipermail/security-announce/2010/000082.html
http://marc.info/?l=bugtraq&m=130168580504508&w=2
http://marc.info/?l=bugtraq&m=136482797910018&w=2
http://secunia.com/advisories/37629
http://secunia.com/advisories/37922
http://secunia.com/advisories/38764
http://secunia.com/advisories/38794
http://secunia.com/advisories/38832
http://secunia.com/advisories/38834
http://secunia.com/advisories/39593
http://security-tracker.debian.org/tracker/CVE-2009-3563
http://securitytracker.com/id?1023298
http://sunsolve.sun.com/search/document.do?assetkey=1-77-1021781.1-1
http://support.avaya.com/css/P8/documents/100071808
http://support.ntp.org/bin/view/Main/SecurityNotice#DoS_attack_from_certain_NTP_mode Patch
http://www-01.ibm.com/support/docview.wss?uid=isg1IZ68659
http://www-01.ibm.com/support/docview.wss?uid=isg1IZ71047
http://www.debian.org/security/2009/dsa-1948 Patch
http://www.kb.cert.org/vuls/id/568372 PatchUS Government Resource
http://www.kb.cert.org/vuls/id/MAPG-7X7V6J
http://www.kb.cert.org/vuls/id/MAPG-7X7VD7
http://www.securityfocus.com/bid/37255 Patch
http://www.vupen.com/english/advisories/2010/0510
http://www.vupen.com/english/advisories/2010/0528
http://www.vupen.com/english/advisories/2010/0993
https://bugzilla.redhat.com/show_bug.cgi?id=531213
https://lists.ntp.org/pipermail/announce/2009-December/000086.html
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11225
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12141
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19376
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7076
https://rhn.redhat.com/errata/RHSA-2009-1648.html
https://rhn.redhat.com/errata/RHSA-2009-1651.html
https://rhn.redhat.com/errata/RHSA-2010-0095.html
https://support.ntp.org/bugs/show_bug.cgi?id=1331

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2018-12327Ntp out-of-bounds write vulnerabilityStack-based buffer overflow in ntpq and ntpdc of NTP version 4.2.8p11 allows an attacker to achieve code execution or escalate to higher privileges v…EPSS 28%9.8CVE-2018-7183Ntp out-of-bounds write vulnerabilityBuffer overflow in the decodearr function in ntpq in ntp 4.2.8p6 through 4.2.8p10 allows remote attackers to execute arbitrary code by leveraging an …EPSS 10%9.8CVE-2015-7705Ntp improper input validation vulnerabilityThe rate limiting feature in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to have unspecified impact via a large number of …EPSS 12%9.8CVE-2015-7853Ntp classic buffer overflow vulnerabilityThe datalen parameter in the refclock driver in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to execute arbitrary code o…EPSS 12%9.8CVE-2015-7871ntpd Crypto-NAK packets bypass authenticationntpd in NTP 4.2.x before 4.2.8p4 and 4.3.x before 4.3.77 mishandles Crypto-NAK packets, allowing remote attackers to bypass authentication. Because N…EPSS 82%analysed8.8CVE-2015-7849Ntp use after free vulnerabilityUse-after-free vulnerability in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to possibly execute arbit…EPSS 17%8.8CVE-2015-7854Ntp classic buffer overflow vulnerabilityBuffer overflow in the password management functionality in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to ca…EPSS 15%8.8CVE-2017-6458Ntp memory buffer overflow vulnerabilityMultiple buffer overflows in the ctl_put* functions in NTP before 4.2.8p10 and 4.3.x before 4.3.94 allow remote authenticated users to have unspecifi…EPSS 6.5%

Source: NIST National Vulnerability Database (record CVE-2009-3563), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.