CVE-2021-20844

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure.

Exploit odds

1.0% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-11-24 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:34 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.0% in the next 30 days (EPSS).
• Severity: 5.7 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-11-24 16:15 UTC

Last modified

2026-06-17 03:34 UTC

Exploit probability

1.0% · EPSS, next 30 days

Weakness

CWE-116

Record status

Modified

Affected

• Yamaha rtx830 Firmware ≤ 15.02.17
• Yamaha nvr510 Firmware ≤ 15.01.18
• Yamaha nvr700w Firmware ≤ 15.00.19
• Yamaha rtx1210 Firmware ≤ 14.01.38
• ntt-west Biz Box rtx830 Firmware ≤ 15.02.17
• ntt-west Biz Box nvr510 Firmware < 15.01.18
• ntt-west Biz Box nvr700w Firmware ≤ 15.00.19
• ntt-west Biz Box rtx1210 Firmware ≤ 14.01.38

Attack profile CVSS 3.1 · 5.7

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-20844.md and follow it. Check whether this project is affected by CVE-2021-20844. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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