---
title: "CVE-2013-4206\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-2013-4206?format=md
keywords: index, follow
---

# CVE-2013-4206

Publication date 19 August 2013

Last updated 24 July 2024

---

Ubuntu priority

**Medium**

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

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## Description

Heap-based buffer underflow in the modmul function in sshbn.c in PuTTY
before 0.63 allows remote SSH servers to cause a denial of service (crash)
and possibly trigger memory corruption or code execution via a crafted DSA
signature, which is not properly handled when performing certain
bit-shifting operations during modular multiplication.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| putty | 13.04 raring | Fixed 0.62-10ubuntu0.1 |
| 12.10 quantal | Fixed 0.62-9ubuntu0.1 |
| 12.04 LTS precise | Fixed 0.62-6ubuntu0.1 |
| 10.04 LTS lucid | Ignored end of life |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-4206)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2013-4206)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2013-4206)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2013-4206)

### Other references

* <http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-modmul.html>
* <https://www.cve.org/CVERecord?id=CVE-2013-4206>