CVE-2021-20844

Name: CVE-2021-20844
Creator: NVD / NIST
Published: 2021-11-24T16:15:13.28+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.7/10EPSS 0.93%

Last modified Jun 17, 2026

CVE-2021-20844 is a medium-severity vulnerability rated 5.7/10 on the CVSS scale. 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.. EPSS estimates a 0.93% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.7/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

EPSS Probability

0.93%

55.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-116

Affected Software

Vendor	Product	Versions
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

References

http://www.rtpro.yamaha.co.jp/RT/FAQ/Security/JVNVU91161784.htmlMitigation, Vendor Advisory
https://business.ntt-east.co.jp/topics/2021/11_09.htmlMitigation, Vendor Advisory
https://jvn.jp/en/vu/JVNVU91161784/index.htmlMitigation, Third Party Advisory
https://www.ntt-west.co.jp/smb/kiki_info/info/211109.htmlMitigation, Vendor Advisory
http://www.rtpro.yamaha.co.jp/RT/FAQ/Security/JVNVU91161784.htmlMitigation, Vendor Advisory
https://business.ntt-east.co.jp/topics/2021/11_09.htmlMitigation, Vendor Advisory
https://jvn.jp/en/vu/JVNVU91161784/index.htmlMitigation, Third Party Advisory
https://www.ntt-west.co.jp/smb/kiki_info/info/211109.htmlMitigation, Vendor Advisory

Timeline

Published: Nov 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20844?

How severe is CVE-2021-20844?

CVE-2021-20844 has a CVSS score of 5.7/10 (MEDIUM severity). The EPSS model estimates a 0.93% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20844?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20844?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST