# CVE-2013-4206: Memory corruption in n/a

> Remote SSH servers can crash PuTTY or potentially execute code via a crafted DSA signature due to a heap buffer underflow.

- **Severity:** Medium 6.8 (`AV:N/AC:M/Au:N/C:P/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:** 19 Aug 2013
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2013-4206, GHSA-h3qw-gcpw-f6mg

## What is CVE-2013-4206?

CVE-2013-4206 is a medium-severity memory corruption vulnerability in n/a, published on 19 Aug 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2013-4206?

It affects 2 products.


Products: Putty Putty, Simon Tatham Putty.

## How do I fix CVE-2013-4206?

Upgrade to a fixed version.

## Is CVE-2013-4206 being exploited?

There is no known exploitation of CVE-2013-4206 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2004-1008](https://insights.sbomify.com/CVE-2004-1008/): Integer overflow in n/a (critical 10.0)
- [CVE-2019-17067](https://insights.sbomify.com/CVE-2019-17067/): Other in n/a (critical 9.8)
- [CVE-2021-36367](https://insights.sbomify.com/CVE-2021-36367/): Auth bypass in n/a (high 8.1)
- [CVE-2016-6167](https://insights.sbomify.com/CVE-2016-6167/): Other in n/a (high 7.8)
- [CVE-2021-33500](https://insights.sbomify.com/CVE-2021-33500/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-4206 and fix it if it is affected.

What it is: CVE-2013-4206 is a medium-severity memory corruption vulnerability in n/a, published on 19 Aug 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2013-4206 in the wild and no public exploit code.

Affected product: n/a. 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-2013-4206/ (Markdown: https://insights.sbomify.com/CVE-2013-4206/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-4206
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-4206
- OSV: https://osv.dev/vulnerability/CVE-2013-4206

---
From sbomify Insights: https://insights.sbomify.com/CVE-2013-4206/
Summaries are generated and may contain mistakes; the official description above is the record.