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)
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.
Noroxi analysis
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We use this product, ask for help- Published
- Dec 9, 2009
- Updated
- Jun 16, 2026
- EPSS
- 32.1% · 98th percentile
- CWE
- —
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Report tools
Action score
35
Monitor
Low priority for now.
- CVSS
- 25 / 40 · 6.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 10 / 30 · 32.1%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| ntp | ntp | cpe:2.3:a:ntp:ntp |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- ntp ntpup to 4.2.2p4 inclusive
- ntp ntp4.0.72
- ntp ntp4.0.73
- ntp ntp4.0.90
- ntp ntp4.0.91
- ntp ntp4.0.92
- ntp ntp4.0.93
- ntp ntp4.0.94
- ntp ntp4.0.95
- ntp ntp4.0.96
- ntp ntp4.0.97
- ntp ntp4.0.98
- ntp ntp4.0.99
- ntp ntp4.1.0
- ntp ntp4.1.2
- ntp ntp4.2.0
- ntp ntp4.2.2
- ntp ntp4.2.2p1
- ntp ntp4.2.2p2
- ntp ntp4.2.2p3
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:11 | ntp | before 1:4.2.4p8+dfsg-1 | 1:4.2.4p8+dfsg-1 |
| Debian:4.0 | ntp | before 1:4.2.2.p4+dfsg-2etch4 | 1:4.2.2.p4+dfsg-2etch4 |
| Debian:5.0 | ntp | before 1:4.2.4p4+dfsg-8lenny3 | 1:4.2.4p4+dfsg-8lenny3 |
| Red Hat:enterprise_linux:3::as | ntp | before 0:4.1.2-6.el3 | 0:4.1.2-6.el3 |
| Red Hat:enterprise_linux:3::as | ntp-debuginfo | before 0:4.1.2-6.el3 | 0:4.1.2-6.el3 |
| Red Hat:enterprise_linux:4::as | ntp | before 0:4.2.0.a.20040617-8.el4_8.1 | 0:4.2.0.a.20040617-8.el4_8.1 |
| Red Hat:enterprise_linux:4::as | ntp-debuginfo | before 0:4.2.0.a.20040617-8.el4_8.1 | 0:4.2.0.a.20040617-8.el4_8.1 |
| Red Hat:enterprise_linux:5::client | ntp | before 0:4.2.2p1-9.el5_4.1 | 0:4.2.2p1-9.el5_4.1 |
| Red Hat:enterprise_linux:5::client | ntp-debuginfo | before 0:4.2.2p1-9.el5_4.1 | 0:4.2.2p1-9.el5_4.1 |
Same product
ntp: all recordsOther highest-scoring records for the same primary product.
- CVE-2015-7871Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.64This week
- CVE-2014-9295Multiple stack-based buffer overflows in ntpd in NTP before 4.2.8 allow remote attackers to execute arbitrary code via a crafted packet, rel54Plan
- CVE-2013-5211The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a denial of service (traffic amplificat49Plan
- CVE-2018-12327Stack-based buffer overflow in ntpq and ntpdc of NTP version 4.2.8p11 allows an attacker to achieve code execution or escalate to higher pri47Plan
- CVE-2016-7434The read_mru_list function in NTP before 4.2.8p9 allows remote attackers to cause a denial of service (crash) via a crafted mrulist query.46Plan
- CVE-2015-7853The 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 arbitra43Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:ntp | 1:4.2.4p8+dfsg-1 · Debian:11 | Package registry (OSV) |
| red hat:ntp | 0:4.2.0.a.20040617-8.el4_8.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ntp-debuginfo | 0:4.2.0.a.20040617-8.el4_8.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Metasploit module ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Metasploit module | auxiliary/dos/ntp/ntpd_reserved_dosNTP.org ntpd Reserved Mode Denial of Serviceauxiliary | 2009-10-04 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Metasploit-67 d
- Published
- TodaySep 30, 2026+6139 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- None
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
—
CVSS vector
AV:N/AC:L/Au:N/C:N/I:P/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- ftp://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?bug=560074
- kb.juniper.net/InfoCenter/index?page=content&id=JSA10673
- kb.juniper.net/InfoCenter/index?page=content&id=JSA10691
- lists.vmware.com/pipermail/security-announce/2010/000082.html
- marc.info/?l=bugtraq&m=130168580504508&w=2
- marc.info/?l=bugtraq&m=136482797910018&w=2
- 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
- security-tracker.debian.org/tracker/CVE-2009-3563
- securitytracker.com/id?1023298
- sunsolve.sun.com/search/document.do?assetkey=1-77-1021781.1-1
- support.avaya.com/css/P8/documents/100071808
- support.ntp.org/bin/view/Main/SecurityNotice#DoS_attack_from_certain_NTP_mode
Vendor advisories and official records. Exploit/PoC links are deliberately left out.