# CVE-2021-20844: Cross-site scripting in RTX830, NVR510, NVR700W, RTX1210

> A remote authenticated attacker can obtain sensitive information via a specially crafted web page due to improper neutralization of HTTP request headers in the Web GUI.

- **Severity:** Medium 5.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/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:** 24 Nov 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-gpv9-mf3p-h34x

## What is CVE-2021-20844?

CVE-2021-20844 is a medium-severity cross-site scripting vulnerability in Yamaha Corporation RTX830, NVR510, NVR700W, RTX1210, published on 24 Nov 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

Improper neutralization of HTTP request headers for scripting syntax vulnerability in the Web GUI of RTX830 Rev.15.02.17 and earlier, NVR510 Rev.15.01.18 and earlier, NVR700W Rev.15.00.19 and earlier, and RTX1210 Rev.14.01.38 and earlier allows a remote authenticated attacker to obtain sensitive information via a specially crafted web page.

Weakness: CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2021-20844?

It affects 8 products.


Products: Ntt-West Biz Box Nvr510 Firmware, Ntt-West Biz Box Nvr700w Firmware, Ntt-West Biz Box Rtx1210 Firmware, Ntt-West Biz Box Rtx830 Firmware, Yamaha Nvr510 Firmware, Yamaha Nvr700w Firmware, Yamaha Rtx1210 Firmware, Yamaha Rtx830 Firmware.

## How do I fix CVE-2021-20844?

No fix has been published for CVE-2021-20844 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20844 being exploited?

There is no known exploitation of CVE-2021-20844 in the wild and no public exploit code.

## Other vulnerabilities in Yamaha Corporation RTX830, NVR510, NVR700W, RTX1210

- [CVE-2021-20843](https://insights.sbomify.com/CVE-2021-20843/): Cross-site scripting in RTX830, NVR510, NVR700W, RTX1210 (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20844 and fix it if it is affected.

What it is: CVE-2021-20844 is a medium-severity cross-site scripting vulnerability in Yamaha Corporation RTX830, NVR510, NVR700W, RTX1210, published on 24 Nov 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-2021-20844 in the wild and no public exploit code.

Affected product: Yamaha Corporation RTX830, NVR510, NVR700W, RTX1210. 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-2021-20844/ (Markdown: https://insights.sbomify.com/CVE-2021-20844/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20844
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20844
- OSV: https://osv.dev/vulnerability/CVE-2021-20844

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20844/
Summaries are generated and may contain mistakes; the official description above is the record.