# CVE-2011-2523: Command injection in vsftpd

> A backdoor in specific compromised builds of vsftpd allows attackers to execute arbitrary commands via a shell on port 6200.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Nov 2019
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-qf3g-hgw2-8r8h

## What is CVE-2011-2523?

CVE-2011-2523 is a critical command injection vulnerability in Debian Debian Linux, published on 27 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

vsftpd 2.3.4 downloaded between 20110630 and 20110703 contains a backdoor which opens a shell on port 6200/tcp.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2011-2523?

It affects 2 products.


Products: Debian Debian Linux, Vsftpd Project Vsftpd.

## How do I fix CVE-2011-2523?

No fix has been published for CVE-2011-2523 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-2523 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-2523 exists.

Public exploit code:

- Python exploit for vsftpd 2.3.4 - Backdoor Command Execution (github_poc): https://github.com/padsalatushal/CVE-2011-2523
- Python exploit for vsftpd 2.3.4 - Backdoor Command Execution (github_poc): https://github.com/Lynk4/CVE-2011-2523
- Exploit para explotar la vulnerabilidad CVE-2011-2523 presente en la versión 2.3.4 de vsftpd. (github_poc): https://github.com/Maalfer/CVE-2011-2523-vsftpd-2.3.4-exploit
- Python exploit for CVE-2011-2523 (VSFTPD 2.3.4 Backdoor Command Execution) (github_poc): https://github.com/4m3rr0r/CVE-2011-2523-poc
- Python exploit for vsftpd 2.3.4 - Backdoor Command Execution (github_poc): https://github.com/BolivarJ/CVE-2011-2523
- vsftpd 2.3.4 Backdoor Exploit (github_poc): https://github.com/nobodyatall648/CVE-2011-2523

## 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-2011-2523 and fix it if it is affected.

What it is: CVE-2011-2523 is a critical command injection vulnerability in Debian Debian Linux, published on 27 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-2523 exists.

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-2011-2523/ (Markdown: https://insights.sbomify.com/CVE-2011-2523/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-2523
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-2523
- OSV: https://osv.dev/vulnerability/CVE-2011-2523

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-2523/
Summaries are generated and may contain mistakes; the official description above is the record.