# CVE-2009-3563: Denial of service in n/a

> Remote attackers can cause denial of service in NTP daemons by sending spoofed MODE_PRIVATE packets, triggering infinite error response loops.

- **Severity:** Medium 6.4 (`AV:N/AC:L/Au:N/C:N/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2009
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2009-3563, DSA-1948-1, GHSA-gm22-x89c-4h54, RHSA-2009:1648

## What is CVE-2009-3563?

CVE-2009-3563 is a medium-severity denial of service vulnerability in Ntp Ntp, published on 9 Dec 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

## Which versions are affected by CVE-2009-3563?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ntp` | Red Hat:enterprise_linux:4::as | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:4::as | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp` | Red Hat:enterprise_linux:4::desktop | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:4::desktop | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp` | Red Hat:enterprise_linux:4::es | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:4::es | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp` | Red Hat:enterprise_linux:4::ws | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:4::ws | All versions | 0:4.2.0.a.20040617-8.el4_8.1 |
| `ntp` | Red Hat:enterprise_linux:5::client | All versions | 0:4.2.2p1-9.el5_4.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:5::client | All versions | 0:4.2.2p1-9.el5_4.1 |
| `ntp` | Red Hat:enterprise_linux:5::server | All versions | 0:4.2.2p1-9.el5_4.1 |
| `ntp-debuginfo` | Red Hat:enterprise_linux:5::server | All versions | 0:4.2.2p1-9.el5_4.1 |

Products: Ntp Ntp.

## How do I fix CVE-2009-3563?

Upgrade to a fixed version.

## Is CVE-2009-3563 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-3563 exists.

Public exploit code:

- NTP.org ntpd Reserved Mode Denial of Service (metasploit)

## Other vulnerabilities in Ntp Ntp

- [CVE-2018-12327](https://insights.sbomify.com/CVE-2018-12327/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-6460](https://insights.sbomify.com/CVE-2017-6460/): Memory corruption in n/a (high 8.8)
- [CVE-2019-11331](https://insights.sbomify.com/CVE-2019-11331/): Other in n/a (high 8.1)
- [CVE-2017-6451](https://insights.sbomify.com/CVE-2017-6451/): Memory corruption in n/a (high 7.8)
- [CVE-2017-6452](https://insights.sbomify.com/CVE-2017-6452/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-3563 and fix it if it is affected.

What it is: CVE-2009-3563 is a medium-severity denial of service vulnerability in Ntp Ntp, published on 9 Dec 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-3563 exists.

Affected product: Ntp Ntp. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2009-3563/ (Markdown: https://insights.sbomify.com/CVE-2009-3563/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-3563
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-3563
- OSV: https://osv.dev/vulnerability/CVE-2009-3563

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-3563/
Summaries are generated and may contain mistakes; the official description above is the record.