CVE-2021-20844

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.

Published: 2021-11-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20844 is rated Moderate Risk (42.4/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.34%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-20844

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.38% 0.34% -0.04%
2 2025-11-18 0.34% 0.38% +0.04%
3 2025-03-30 — 0.34% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20844

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.1 3.6 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 6.8 2.9 [email protected]

Weakness enumeration for CVE-2021-20844

Affected software / configurations for CVE-2021-20844

Vendor Product Version Raw CPE
yamaha rtx830_firmware <= 15.02.17 cpe:2.3:o:yamaha:rtx830_firmware:*:*:*:*:*:*:*:*
yamaha nvr510_firmware <= 15.01.18 cpe:2.3:o:yamaha:nvr510_firmware:*:*:*:*:*:*:*:*
yamaha nvr700w_firmware <= 15.00.19 cpe:2.3:o:yamaha:nvr700w_firmware:*:*:*:*:*:*:*:*
yamaha rtx1210_firmware <= 14.01.38 cpe:2.3:o:yamaha:rtx1210_firmware:*:*:*:*:*:*:*:*
ntt-west biz_box_rtx830_firmware <= 15.02.17 cpe:2.3:o:ntt-west:biz_box_rtx830_firmware:*:*:*:*:*:*:*:*
ntt-west biz_box_nvr510_firmware < 15.01.18 cpe:2.3:o:ntt-west:biz_box_nvr510_firmware:*:*:*:*:*:*:*:*
ntt-west biz_box_nvr700w_firmware <= 15.00.19 cpe:2.3:o:ntt-west:biz_box_nvr700w_firmware:*:*:*:*:*:*:*:*
ntt-west biz_box_rtx1210_firmware <= 14.01.38 cpe:2.3:o:ntt-west:biz_box_rtx1210_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-20844

cvelogic Threat Intelligence