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Fencer Vulns
medium 6.4

CVE-2009-3563 json

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…

published 2009-12-09 16 y ago modified 2026-06-16 4 mo ago also EUVD-2009-3544

cvss
6.4
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
32.1%
EPSS 32.1% chance of exploitation in 30 days, percentile 98%
public exploits
1
Metasploit

Summary

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.

Patch / fix

  • ntp Debian 11 1:4.2.4p8+dfsg-1

debian advisories DEBIAN-CVE-2009-3563

  • ntp RHEL 3 4.1.2-6.el3
  • ntp RHEL 4 4.2.0.a.20040617-8.el4_8.1
  • ntp RHEL 5 4.2.2p1-9.el5_4.1

red hat advisories RHSA-2009:1651RHSA-2009:1648

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2009-3563 updated cvss 5.0

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

  • Red Hat Desktop version 3 ntp 4.1.2-6.el3
    fixed: vendor fix RHSA-2009:1651
  • Red Hat Enterprise Linux (v. 5 server) ntp 4.2.2p1-9.el5_4.1
    fixed: vendor fix RHSA-2009:1648
  • Red Hat Enterprise Linux AS version 3 ntp 4.1.2-6.el3
    fixed: vendor fix RHSA-2009:1651
  • Red Hat Enterprise Linux AS version 4 ntp 4.2.0.a.20040617-8.el4_8.1 Red Hat Enterprise Linux Desktop (v. 5 client) ntp 4.2.2p1-9.el5_4.1 Red Hat Enterprise Linux Desktop version 4 ntp 4.2.0.a.20040617-8.el4_8.1
    fixed: vendor fix RHSA-2009:1648
  • Red Hat Enterprise Linux ES version 3 ntp 4.1.2-6.el3
    fixed: vendor fix RHSA-2009:1651
  • Red Hat Enterprise Linux ES version 4 ntp 4.2.0.a.20040617-8.el4_8.1
    fixed: vendor fix RHSA-2009:1648
  • Red Hat Enterprise Linux WS version 3 ntp 4.1.2-6.el3
    fixed: vendor fix RHSA-2009:1651
  • Red Hat Enterprise Linux WS version 4 ntp 4.2.0.a.20040617-8.el4_8.1
    fixed: vendor fix RHSA-2009:1648

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (Metasploit auxiliary/dos/ntp/ntpd_reserved_dos)
  2. Published

Exploit prediction

32.06% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

CVSS scores

assigned by version score vector
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:N/I:P/A:P

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.