# CVE-2021-28800: Command Injection Vulnerability in QTS

> Attackers can execute arbitrary commands on vulnerable QNAP NAS devices via a command injection flaw in legacy QTS versions.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/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:** 24 Jun 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-f7g6-2r8w-qfr2

## What is CVE-2021-28800?

CVE-2021-28800 is a high-severity command injection vulnerability in Qnap Qts, published on 24 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A command injection vulnerability has been reported to affect QNAP NAS running legacy versions of QTS. If exploited, this vulnerability allows attackers to execute arbitrary commands in a compromised application. This issue affects: QNAP Systems Inc. QTS versions prior to 4.3.6.1663 Build 20210504; versions prior to 4.3.3.1624 Build 20210416. This issue does not affect: QNAP Systems Inc. QTS 4.5.3. QNAP Systems Inc. QuTS hero h4.5.3. QNAP Systems Inc. QuTScloud c4.5.5.

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

## Which versions are affected by CVE-2021-28800?

It affects 1 product.


Products: Qnap Qts.

## How do I fix CVE-2021-28800?

No fix has been published for CVE-2021-28800 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28800 being exploited?

There is no known exploitation of CVE-2021-28800 in the wild and no public exploit code.

## Other vulnerabilities in Qnap Qts

- [CVE-2020-2509](https://insights.sbomify.com/CVE-2020-2509/): QNAP Network-Attached Storage (NAS) Command Injection (critical 9.8, exploited in the wild)
- [CVE-2018-19949](https://insights.sbomify.com/CVE-2018-19949/): QNAP NAS File Station Command Injection (critical 9.8, exploited in the wild)
- [CVE-2019-7193](https://insights.sbomify.com/CVE-2019-7193/): QNAP QTS Improper Input Validation (critical 9.8, exploited in the wild)
- [CVE-2018-19943](https://insights.sbomify.com/CVE-2018-19943/): QNAP NAS File Station Cross-Site Scripting (high 8.0, exploited in the wild)
- [CVE-2018-19953](https://insights.sbomify.com/CVE-2018-19953/): QNAP NAS File Station Cross-Site Scripting (medium 6.1, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28800 and fix it if it is affected.

What it is: CVE-2021-28800 is a high-severity command injection vulnerability in Qnap Qts, published on 24 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-2021-28800 in the wild and no public exploit code.

Affected product: Qnap Qts. 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-2021-28800/ (Markdown: https://insights.sbomify.com/CVE-2021-28800/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28800
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28800
- OSV: https://osv.dev/vulnerability/CVE-2021-28800

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28800/
Summaries are generated and may contain mistakes; the official description above is the record.