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CVE-2009-3563

48
FAUCET Score

CVE-2009-3563 is a denial-of-service vulnerability affecting NTP daemons in NTP versions before 4.2.4p8 and 4.2.5. Attackers can exploit this by sending spoofed MODE_PRIVATE requests or responses, triggering an endless loop of error exchanges between two NTP servers, leading to high CPU and bandwidth consumption. This vulnerability has a CVSS score of 6.4, indicating a medium severity, and can be exploited remotely with low attack complexity and no authentication required, resulting in partial impact to integrity and availability. While not listed in CISA's KEV catalog, a Metasploit module exists for exploitation, and it has garnered significant community discussion and media coverage, suggesting awareness and potential for exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
<= 4.2.2p4CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
4.0.72CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.0.72:*:*:*:*:*:*:*
4.0.73CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.0.73:*:*:*:*:*:*:*
4.0.90CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.0.90:*:*:*:*:*:*:*
4.0.91CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.0.91:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

6.4MEDIUM

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

Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
4.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
31.30%
Probability of exploitation in next 30 days
EPSS Percentile
98.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
Metasploit: NTP.org ntpd Reserved Mode Denial of Service · Oct 4, 2009
This CVE's current EPSS score of 0.3130 is in the 98th percentile among its peer group of 23,701 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

debianpatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 3Fixed in: ntp-0:4.1.2-6.el3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: ntp-0:4.2.0.a.20040617-8.el4_8.1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: ntp-0:4.2.2p1-9.el5_4.1
View patch

Vendor Advisories (1)

redhatCVE-2009-3563Moderate

ntpd: DoS with mode 7 packets (VU#568372)

Dec 8, 2009

References

ftp.netbsd.org / pub/NetBSD/security/advisories/NetBSD-SA2010-005.txt.asc
aix.software.ibm.com / aix/efixes/security/xntpd_advisory.asc
bugs.debian.org / cgi-bin/bugreport.cgi
kb.juniper.net / InfoCenter/index
kb.juniper.net / InfoCenter/index
lists.vmware.com / pipermail/security-announce/2010/000082.html
marc.info
marc.info
bugzilla.redhat.com / show_bug.cgi
secunia.com / advisories/37629
secunia.com / advisories/37922
secunia.com / advisories/38764
secunia.com / advisories/38794
secunia.com / advisories/38832
secunia.com / advisories/38834
secunia.com / advisories/39593
securitytracker.com / id
security-tracker.debian.org / tracker/CVE-2009-3563
lists.ntp.org / pipermail/announce/2009-December/000086.html
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11225
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12141
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19376
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7076
rhn.redhat.com / errata/RHSA-2009-1648.html
rhn.redhat.com / errata/RHSA-2009-1651.html
rhn.redhat.com / errata/RHSA-2010-0095.html
support.ntp.org / bugs/show_bug.cgi
sunsolve.sun.com / search/document.do
support.avaya.com / css/P8/documents/100071808
support.ntp.org / bin/view/Main/SecurityNotice
Patch
kb.cert.org / vuls/id/417980
redhat.com / archives/fedora-package-announce/2009-December/msg00763.html
redhat.com / archives/fedora-package-announce/2009-December/msg00809.html
www-01.ibm.com / support/docview.wss
www-01.ibm.com / support/docview.wss
debian.org / security/2009/dsa-1948
Patch
kb.cert.org / vuls/id/568372
PatchUS Government Resource
kb.cert.org / vuls/id/MAPG-7X7V6J
kb.cert.org / vuls/id/MAPG-7X7VD7
securityfocus.com / bid/37255
Patch
vupen.com / english/advisories/2010/0510
vupen.com / english/advisories/2010/0528
vupen.com / english/advisories/2010/0993