# CVE-2021-34761: Cisco Firepower Threat Defense Software CLI Arbitrary File Write Vulnerability

> Authenticated local attackers with admin credentials can overwrite system files via CLI input validation flaws, leading to privilege escalation.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Oct 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-3vcw-92x2-jjg4

## What is CVE-2021-34761?

CVE-2021-34761 is a medium-severity path traversal vulnerability in Cisco Secure Firewall Threat Defense, published on 27 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to overwrite or append arbitrary data to system files using root-level privileges. The attacker must have administrative credentials on the device. This vulnerability is due to incomplete validation of user input for a specific CLI command. An attacker could exploit this vulnerability by authenticating to the device with administrative privileges and issuing a CLI command with crafted user parameters. A successful exploit could allow the attacker to overwrite or append arbitrary data to system files using root-level privileges.

Weakness: CWE-668 (Exposure of Resource to Wrong Sphere), CWE-73 (External Control of File Name or Path)

## Which versions are affected by CVE-2021-34761?

It affects 3 products.


Products: Cisco Firepower Management Center Virtual Appliance, Cisco Secure Firewall Threat Defense, Cisco Sourcefire Defense Center.

## How do I fix CVE-2021-34761?

No fix has been published for CVE-2021-34761 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34761 being exploited?

There is no known exploitation of CVE-2021-34761 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Secure Firewall Threat Defense

- [CVE-2021-34781](https://insights.sbomify.com/CVE-2021-34781/): Cisco Firepower Threat Defense Software SSH Connections Denial of Service Vulnerability (high 8.6)
- [CVE-2021-34762](https://insights.sbomify.com/CVE-2021-34762/): Cisco Firepower Management Center Software Authenticated Directory Traversal Vulnerability (high 8.1)
- [CVE-2021-34755](https://insights.sbomify.com/CVE-2021-34755/): Cisco Firepower Threat Defense Software Command Injection Vulnerabilities (medium 6.7)
- [CVE-2021-34756](https://insights.sbomify.com/CVE-2021-34756/): Cisco Firepower Threat Defense Software Command Injection Vulnerabilities (medium 6.7)
- [CVE-2021-34763](https://insights.sbomify.com/CVE-2021-34763/): Cisco Firepower Management Center Software Cross-Site Scripting and Open Redirect Vulnerabilities (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34761 and fix it if it is affected.

What it is: CVE-2021-34761 is a medium-severity path traversal vulnerability in Cisco Secure Firewall Threat Defense, published on 27 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-34761 in the wild and no public exploit code.

Affected product: Cisco Secure Firewall Threat Defense. 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-2021-34761/ (Markdown: https://insights.sbomify.com/CVE-2021-34761/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34761
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34761
- OSV: https://osv.dev/vulnerability/CVE-2021-34761

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34761/
Summaries are generated and may contain mistakes; the official description above is the record.