# CVE-2021-40120: Cisco Small Business RV Series Routers Command Injection Vulnerability

> Authenticated administrators can inject arbitrary commands to execute code with root privileges on Cisco Small Business RV Series Routers.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Nov 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-f2p2-qfcm-69wm

## What is CVE-2021-40120?

CVE-2021-40120 is a medium-severity command injection vulnerability in Cisco Application Extension Platform, published on 4 Nov 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker with administrative privileges to inject arbitrary commands into the underlying operating system and execute them using root-level privileges. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious input to a specific field in the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system as a user with root-level privileges.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-40120?

It affects 2 products.


Products: Cisco Application Extension Platform, Cisco Ios Xr.

## How do I fix CVE-2021-40120?

No fix has been published for CVE-2021-40120 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40120 being exploited?

There is no known exploitation of CVE-2021-40120 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Application Extension Platform

- [CVE-2021-34730](https://insights.sbomify.com/CVE-2021-34730/): Memory corruption in Cisco Small Business RV Series Router Firmware (critical 9.8)
- [CVE-2021-1146](https://insights.sbomify.com/CVE-2021-1146/): Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Management Interface Command Injection Vulnerabilities (high 7.2)
- [CVE-2021-1147](https://insights.sbomify.com/CVE-2021-1147/): Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Management Interface Command Injection Vulnerabilities (high 7.2)
- [CVE-2021-1148](https://insights.sbomify.com/CVE-2021-1148/): Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Management Interface Command Injection Vulnerabilities (high 7.2)
- [CVE-2021-1149](https://insights.sbomify.com/CVE-2021-1149/): Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Management Interface Command Injection Vulnerabilities (high 7.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40120 and fix it if it is affected.

What it is: CVE-2021-40120 is a medium-severity command injection vulnerability in Cisco Application Extension Platform, published on 4 Nov 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-40120 in the wild and no public exploit code.

Affected product: Cisco Application Extension Platform. 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-2021-40120/ (Markdown: https://insights.sbomify.com/CVE-2021-40120/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40120
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40120
- OSV: https://osv.dev/vulnerability/CVE-2021-40120

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40120/
Summaries are generated and may contain mistakes; the official description above is the record.