---
title: "CVE-2009-1243\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2009-1243?format=md
keywords: index, follow
---

# CVE-2009-1243

Publication date 6 April 2009

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**5.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2009-1243?format=md#impact-score)

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## Description

net/ipv4/udp.c in the Linux kernel before 2.6.29.1 performs an unlocking
step in certain incorrect circumstances, which allows local users to cause
a denial of service (panic) by reading zero bytes from the /proc/net/udp
file and unspecified other files, related to the "udp seq\_file
infrastructure."

[Read the notes from the security team](https://ubuntu.com/security/CVE-2009-1243?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| linux | 9.04 jaunty | Not affected |
| 8.10 intrepid | Not affected |
| 8.04 LTS hardy | Not affected |
| 7.10 gutsy | Not in release |
| 6.06 LTS dapper | Not in release |
| linux-source-2.6.15 | 9.04 jaunty | Not in release |
| 8.10 intrepid | Not in release |
| 8.04 LTS hardy | Not in release |
| 7.10 gutsy | Not in release |
| 6.06 LTS dapper | Not affected |
| linux-source-2.6.22 | 9.04 jaunty | Not in release |
| 8.10 intrepid | Not in release |
| 8.04 LTS hardy | Not in release |
| 7.10 gutsy | Ignored end of life, was needs-triage |
| 6.06 LTS dapper | Not in release |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2009-1243?format=md#patch-details)

## Notes

---

### [smb](https://launchpad.net/~smb)

introducted with v2.6.29-rc1 and fixed in v2.6.30-rc1.

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| linux | * Upstream:   <http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=30842f2989aacfaba3ccb39829b3417be9313dbe> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | Low |
  | Privileges required | Low |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1243)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2009-1243)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2009-1243)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2009-1243)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2009-1243>