# CVE-2021-33841: Circutor SGE-PLC1000 OS command Injection

> Remote attackers can inject OS commands with maximum privileges on Circutor SGE-PLC1000 devices due to improper request handling.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 9 Jun 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-56hw-2q6h-3vh6

## What is CVE-2021-33841?

CVE-2021-33841 is a critical command injection vulnerability in Circutor SGE-PLC1000, published on 9 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SGE-PLC1000 device, in its 0.9.2b firmware version, does not handle some requests correctly, allowing a remote attacker to inject code into the operating system with maximum privileges.

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

## Which versions are affected by CVE-2021-33841?

It affects 1 product.


Products: Circutor Sge-Plc1000 Firmware.

## How do I fix CVE-2021-33841?

No fix has been published for CVE-2021-33841 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33841 being exploited?

There is no known exploitation of CVE-2021-33841 in the wild and no public exploit code.

## Other vulnerabilities in Circutor SGE-PLC1000

- [CVE-2025-11778](https://insights.sbomify.com/CVE-2025-11778/): Stack-based buffer overflow vulnreability in Circutor SGE-PLC1000/SGE-PLC50 (critical 10.0)
- [CVE-2025-11779](https://insights.sbomify.com/CVE-2025-11779/): Stack-based buffer overflow vulnreability in Circutor SGE-PLC1000/SGE-PLC50 (critical 9.4)
- [CVE-2021-33842](https://insights.sbomify.com/CVE-2021-33842/): Circutor SGE-PLC1000 improper authentication (high 8.8)
- [CVE-2025-11780](https://insights.sbomify.com/CVE-2025-11780/): Stack-based buffer overflow vulnreability in Circutor SGE-PLC1000/SGE-PLC50 (high 8.7)
- [CVE-2025-11781](https://insights.sbomify.com/CVE-2025-11781/): Use of hardcoded cryptographic keys in Circutor SGE-PLC1000/SGE-PLC50 (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33841 and fix it if it is affected.

What it is: CVE-2021-33841 is a critical command injection vulnerability in Circutor SGE-PLC1000, published on 9 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-33841 in the wild and no public exploit code.

Affected product: Circutor SGE-PLC1000. 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-2021-33841/ (Markdown: https://insights.sbomify.com/CVE-2021-33841/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33841
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33841
- OSV: https://osv.dev/vulnerability/CVE-2021-33841

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33841/
Summaries are generated and may contain mistakes; the official description above is the record.