# CVE-2021-1531: Cisco Modeling Labs Web UI Command Injection Vulnerability

> Authenticated attackers can execute arbitrary OS commands on Cisco Modeling Labs servers via crafted HTTP requests in the web UI.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 May 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-m74m-f2xh-459p

## What is CVE-2021-1531?

CVE-2021-1531 is a high-severity command injection vulnerability in Cisco Modeling Labs, published on 22 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the web UI of Cisco Modeling Labs could allow an authenticated, remote attacker to execute arbitrary commands with the privileges of the web application on the underlying operating system of an affected Cisco Modeling Labs server. This vulnerability is due to insufficient validation of user-supplied input to the web UI. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected server. A successful exploit could allow the attacker to execute arbitrary commands with the privileges of the web application, virl2, on the underlying operating system of the affected server. To exploit this vulnerability, the attacker must have valid user credentials on the web UI.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command)

## Which versions are affected by CVE-2021-1531?

It affects 1 product.


Products: Cisco Modeling Labs.

## How do I fix CVE-2021-1531?

No fix has been published for CVE-2021-1531 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1531 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-1531 exists.

## Other vulnerabilities in Cisco Modeling Labs

- [CVE-2023-20154](https://insights.sbomify.com/CVE-2023-20154/): Cisco Modeling Labs External Authentication Bypass Vulnerability (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1531 and fix it if it is affected.

What it is: CVE-2021-1531 is a high-severity command injection vulnerability in Cisco Modeling Labs, published on 22 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-1531 exists.

Affected product: Cisco Modeling Labs. 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-2021-1531/ (Markdown: https://insights.sbomify.com/CVE-2021-1531/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1531
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1531
- OSV: https://osv.dev/vulnerability/CVE-2021-1531

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1531/
Summaries are generated and may contain mistakes; the official description above is the record.