# CVE-2021-28803: Stored XSS Vulnerability in Q'center

> Attackers can inject malicious scripts into Q'center, potentially executing code or hijacking user accounts.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 1 Jul 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-5g7h-5qvh-cr9r

## What is CVE-2021-28803?

CVE-2021-28803 is a medium-severity cross-site scripting vulnerability in QNAP Systems Inc. Q'center, published on 1 Jul 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

This issue affects: QNAP Systems Inc. Q'center versions prior to 1.11.1004.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-80 (Improper Neutralization of Script-Related HTML Tags in a Web Page)

## Which versions are affected by CVE-2021-28803?

It affects 1 product.


Products: Qnap Q\'center.

## How do I fix CVE-2021-28803?

No fix has been published for CVE-2021-28803 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28803 being exploited?

There is no known exploitation of CVE-2021-28803 in the wild and no public exploit code.

## Other vulnerabilities in QNAP Systems Inc. Q'center

- [CVE-2018-0706](https://insights.sbomify.com/CVE-2018-0706/): Information disclosure in Q'center Virtual Appliance (high 8.8)
- [CVE-2018-0708](https://insights.sbomify.com/CVE-2018-0708/): Command injection in Q'center Virtual Appliance (high 8.8)
- [CVE-2018-0709](https://insights.sbomify.com/CVE-2018-0709/): Command injection in Q'center Virtual Appliance (high 8.8)
- [CVE-2018-0710](https://insights.sbomify.com/CVE-2018-0710/): Command injection in Q'center Virtual Appliance (high 8.8)
- [CVE-2021-28807](https://insights.sbomify.com/CVE-2021-28807/): Post-Authentication Reflected XSS Vulnerability in Q'center (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28803 and fix it if it is affected.

What it is: CVE-2021-28803 is a medium-severity cross-site scripting vulnerability in QNAP Systems Inc. Q'center, published on 1 Jul 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-28803 in the wild and no public exploit code.

Affected product: QNAP Systems Inc. Q'center. 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-2021-28803/ (Markdown: https://insights.sbomify.com/CVE-2021-28803/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28803
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28803
- OSV: https://osv.dev/vulnerability/CVE-2021-28803

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-28803/
Summaries are generated and may contain mistakes; the official description above is the record.