# CVE-2021-41243: OS Command Injection Vulnerability and Potential Zip Slip Vulnerability

> Authenticated users can upload malicious zip files to execute arbitrary commands on the host operating system via OS command injection.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L`)
- **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:** 26 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-7rpc-9m88-cf9w

## What is CVE-2021-41243?

CVE-2021-41243 is a critical command injection vulnerability in Basercms Basercms, published on 26 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

There is a Potential Zip Slip Vulnerability and OS Command Injection Vulnerability on the management system of baserCMS. Users with permissions to upload files may upload crafted zip files which may execute arbitrary commands on the host operating system. This is a vulnerability that needs to be addressed when the management system is used by an unspecified number of users. If you are eligible, please update to the new version as soon as possible.

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

## Which versions are affected by CVE-2021-41243?

2 open source packages ship an affected version, including baserproject/basercms. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `baserproject/basercms` | Packagist | All versions | 4.5.4 |
| `baserproject/basercms` | Packagist | All versions | 4.5.4 |

Products: Basercms Basercms.

## How do I fix CVE-2021-41243?

Upgrade baserproject/basercms to 4.5.4 or later.

## Is CVE-2021-41243 being exploited?

There is no known exploitation of CVE-2021-41243 in the wild and no public exploit code.

## Other vulnerabilities in Basercms Basercms

- [CVE-2023-25654](https://insights.sbomify.com/CVE-2023-25654/): baserCMS File Uploader Remote Code Execution (RCE) vulnerability (critical 9.8)
- [CVE-2023-25655](https://insights.sbomify.com/CVE-2023-25655/): baserCMS allows any file to be uploaded (critical 9.8)
- [CVE-2017-10842](https://insights.sbomify.com/CVE-2017-10842/): baserCMS SQL Injection vulnerability (critical 9.8)
- [CVE-2026-30880](https://insights.sbomify.com/CVE-2026-30880/): baserCMS: OS command injection vulnerability in installer (critical 9.2)
- [CVE-2026-21861](https://insights.sbomify.com/CVE-2026-21861/): baserCMS: OS Command Injection Leading to Remote Code Execution (RCE) (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41243 and fix it if it is affected.

What it is: CVE-2021-41243 is a critical command injection vulnerability in Basercms Basercms, published on 26 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-41243 in the wild and no public exploit code.

Affected packages and fixed versions:
- baserproject/basercms (Packagist): affected all versions; fixed in 4.5.4
- baserproject/basercms (Packagist): affected all versions; fixed in 4.5.4

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-2021-41243/ (Markdown: https://insights.sbomify.com/CVE-2021-41243/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41243
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41243
- OSV: https://osv.dev/vulnerability/CVE-2021-41243

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41243/
Summaries are generated and may contain mistakes; the official description above is the record.