# CVE-2020-2503: Stored cross-site scripting vulnerability in QES

> Remote attackers can inject malicious scripts into QNAP QES File Station, potentially leading to code execution or account takeover.

- **Severity:** Critical 9.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H`)
- **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:** 24 Dec 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-v96c-c8j8-qhm7

## What is CVE-2020-2503?

CVE-2020-2503 is a critical cross-site scripting vulnerability in QNAP Systems Inc. QES, published on 24 Dec 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

If exploited, this stored cross-site scripting vulnerability could allow remote attackers to inject malicious code in File Station. QNAP has already fixed these issues in QES 2.1.1 Build 20201006 and later.

Weakness: CWE-80 (Improper Neutralization of Script-Related HTML Tags in a Web Page), CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-749 (Exposed Dangerous Method or Function)

## Which versions are affected by CVE-2020-2503?

It affects 1 product.


Products: Qnap Qes.

## How do I fix CVE-2020-2503?

No fix has been published for CVE-2020-2503 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-2503 being exploited?

There is no known exploitation of CVE-2020-2503 in the wild and no public exploit code.

## Other vulnerabilities in QNAP Systems Inc. QES

- [CVE-2020-2499](https://insights.sbomify.com/CVE-2020-2499/): Hard-coded Password Vulnerability in QES (medium 6.3)
- [CVE-2020-2504](https://insights.sbomify.com/CVE-2020-2504/): Absolute path traversal vulnerability in QES (medium 5.8)
- [CVE-2020-2505](https://insights.sbomify.com/CVE-2020-2505/): Sensitive information via generation of error messages vulnerability in QES (low 2.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-2503 and fix it if it is affected.

What it is: CVE-2020-2503 is a critical cross-site scripting vulnerability in QNAP Systems Inc. QES, published on 24 Dec 2020. 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-2020-2503 in the wild and no public exploit code.

Affected product: QNAP Systems Inc. QES. 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-2020-2503/ (Markdown: https://insights.sbomify.com/CVE-2020-2503/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-2503
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-2503
- OSV: https://osv.dev/vulnerability/CVE-2020-2503

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-2503/
Summaries are generated and may contain mistakes; the official description above is the record.