# CVE-2021-38691: Stack Overflow Vulnerability in QVR Elite, QVR Pro and QVR Guard

> Attackers can execute arbitrary code on QNAP devices via a stack buffer overflow in QVR surveillance applications.

- **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:** 14 Jan 2022
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-98m9-234r-rmcv

## What is CVE-2021-38691?

CVE-2021-38691 is a high-severity memory corruption vulnerability in QNAP Systems Inc. QVR Elite, published on 14 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A stack buffer overflow vulnerability has been reported to affect QNAP device running QVR Elite, QVR Pro, QVR Guard. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of QVR Elite, QVR Pro, QVR Guard: QuTS hero h5.0.0: QVR Elite 2.1.4.0 (2021/12/06) and later QuTS hero h4.5.4: QVR Elite 2.1.4.0 (2021/12/06) and later QTS 5.0.0: QVR Elite 2.1.4.0 (2021/12/06) and later QTS 4.5.4: QVR Elite 2.1.4.0 (2021/12/06) and later QTS 4.5.4: QVR Pro 2.1.3.0 (2021/12/06) and later QTS 5.0.0: QVR Pro 2.1.3.0 (2021/12/06) and later QTS 4.5.4: QVR Guard 2.1.3.0 (2021/12/06) and later QTS 5.0.0: QVR Guard 2.1.3.0 (2021/12/06) and later

Weakness: CWE-787 (Out-of-bounds Write), CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2021-38691?

It affects 3 products.


Products: Qnap Qvr Elite, Qnap Qvr Guard, Qnap Qvr Pro.

## How do I fix CVE-2021-38691?

No fix has been published for CVE-2021-38691 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-38691 being exploited?

There is no known exploitation of CVE-2021-38691 in the wild and no public exploit code.

## Other vulnerabilities in QNAP Systems Inc. QVR Elite

- [CVE-2021-38682](https://insights.sbomify.com/CVE-2021-38682/): Stack Overflow Vulnerability in QVR Elite, QVR Pro and QVR Guard (high 8.1)
- [CVE-2021-38689](https://insights.sbomify.com/CVE-2021-38689/): Stack Overflow Vulnerability in QVR Elite, QVR Pro and QVR Guard (high 8.1)
- [CVE-2021-38690](https://insights.sbomify.com/CVE-2021-38690/): Stack Overflow Vulnerability in QVR Elite, QVR Pro and QVR Guard (high 8.1)
- [CVE-2021-38692](https://insights.sbomify.com/CVE-2021-38692/): Stack Overflow Vulnerability in QVR Elite, QVR Pro and QVR Guard (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-38691 and fix it if it is affected.

What it is: CVE-2021-38691 is a high-severity memory corruption vulnerability in QNAP Systems Inc. QVR Elite, published on 14 Jan 2022. 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-2021-38691 in the wild and no public exploit code.

Affected product: QNAP Systems Inc. QVR Elite. 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-2021-38691/ (Markdown: https://insights.sbomify.com/CVE-2021-38691/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-38691
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-38691
- OSV: https://osv.dev/vulnerability/CVE-2021-38691

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-38691/
Summaries are generated and may contain mistakes; the official description above is the record.