MEDIUM
CVE-2009-3563
NVD-CWE-OtherPublished: December 9, 2009· Updated: Jun 16, 2026
6.4
CVSS v3.1
Official 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.
Technical Analysis
CVE-2009-3563 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.
User Interaction
Scope
Impact
ConfidentialityNone
IntegrityP
AvailabilityP
AV:N/AC:L/Au:N/C:N/I:P/A:P
Affected Vendors & Products
ntp1 product(s)
ntp
Source: NVD CPE · 21 total CPE entries
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
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Rapid7 / Metasploit
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Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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Official Patches & Advisories
All References (86)
Quick Facts
CVE IDCVE-2009-3563
CVSS Score6.4 / 10
SeverityMEDIUM
WeaknessNVD-CWE-Other
CISA KEVNo
Affected1 vendor(s)
PublishedDec 9, 2009
Related CVEs (NVD-CWE-Other)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2009-3563 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.