# CVE-2012-0920: Use after free in n/a

> Remote authenticated users can execute arbitrary code and bypass command restrictions in Dropbear SSH Server when specific authentication and restriction features are enabled.

- **Severity:** High 7.1 (`AV:N/AC:H/Au:S/C:C/I:C/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Jun 2012
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2012-0920, DSA-2456-1, GHSA-hw56-hwpj-4432

## What is CVE-2012-0920?

CVE-2012-0920 is a high-severity use after free vulnerability in Debian Debian Linux, published on 5 Jun 2012. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Use-after-free vulnerability in Dropbear SSH Server 0.52 through 2012.54, when command restriction and public key authentication are enabled, allows remote authenticated users to execute arbitrary code and bypass command restrictions via multiple crafted command requests, related to "channels concurrency."

Weakness: CWE-399

## Which versions are affected by CVE-2012-0920?

It affects 2 products.


Products: Debian Debian Linux, Dropbear Ssh Project Dropbear Ssh.

## How do I fix CVE-2012-0920?

Apply the vendor's patch.

## Is CVE-2012-0920 being exploited?

There is no known exploitation of CVE-2012-0920 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2012-0920 and fix it if it is affected.

What it is: CVE-2012-0920 is a high-severity use after free vulnerability in Debian Debian Linux, published on 5 Jun 2012. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2012-0920 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2012-0920/ (Markdown: https://insights.sbomify.com/CVE-2012-0920/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2012-0920
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2012-0920
- OSV: https://osv.dev/vulnerability/CVE-2012-0920

---
From sbomify Insights: https://insights.sbomify.com/CVE-2012-0920/
Summaries are generated and may contain mistakes; the official description above is the record.