# CVE-2011-0539: Information disclosure in n/a

> Remote attackers can obtain sensitive stack memory contents or facilitate hash collisions when generating legacy certificates with uninitialized nonce fields.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Feb 2011
- **Updated:** 29 May 2026
- **Also known as:** DEBIAN-CVE-2011-0539, GHSA-395x-3x8q-mv38

## What is CVE-2011-0539?

CVE-2011-0539 is a high-severity vulnerability in OpenSSH, published on 10 Feb 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The key_certify function in usr.bin/ssh/key.c in OpenSSH 5.6 and 5.7, when generating legacy certificates using the -t command-line option in ssh-keygen, does not initialize the nonce field, which might allow remote attackers to obtain sensitive stack memory contents or make it easier to conduct hash collision attacks.

Weakness: CWE-264, CWE-457 (Use of Uninitialized Variable)

## Which versions are affected by CVE-2011-0539?

It affects 1 product.


Products: OpenSSH.

## How do I fix CVE-2011-0539?

Apply the vendor's patch.

## Is CVE-2011-0539 being exploited?

There is no known exploitation of CVE-2011-0539 in the wild and no public exploit code.

## Other vulnerabilities in OpenSSH

- [CVE-2003-0786](https://insights.sbomify.com/CVE-2003-0786/): Auth bypass in n/a (critical 10.0)
- [CVE-2003-0693](https://insights.sbomify.com/CVE-2003-0693/): Memory corruption in n/a (critical 10.0)
- [CVE-2002-0640](https://insights.sbomify.com/CVE-2002-0640/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0144](https://insights.sbomify.com/CVE-2001-0144/): Integer overflow in n/a (critical 10.0)
- [CVE-2000-0999](https://insights.sbomify.com/CVE-2000-0999/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-0539 and fix it if it is affected.

What it is: CVE-2011-0539 is a high-severity vulnerability in OpenSSH, published on 10 Feb 2011. 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-2011-0539 in the wild and no public exploit code.

Affected product: OpenSSH. 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-2011-0539/ (Markdown: https://insights.sbomify.com/CVE-2011-0539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-0539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-0539
- OSV: https://osv.dev/vulnerability/CVE-2011-0539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-0539/
Summaries are generated and may contain mistakes; the official description above is the record.