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CVE-2021-20844

21
FAUCET Score

CVE-2021-20844 is an improper neutralization of HTTP request headers vulnerability affecting the Web GUI of specific Yamaha RTX and NVR series devices. A remote, authenticated attacker can exploit this flaw by tricking a user into visiting a specially crafted web page, leading to the disclosure of sensitive information. With a CVSS score of 5.7 (Medium), this vulnerability requires user interaction and authenticated access, but can result in high confidentiality impact. There is currently no public exploit code available, it is not listed in CISA's KEV catalog, and it has received minimal community discussion or media coverage, suggesting low active exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
<= 15.02.17CPE matchmatch criteria
cpe:2.3:o:yamaha:rtx830_firmware:*:*:*:*:*:*:*:*
<= 15.01.18CPE matchmatch criteria
cpe:2.3:o:yamaha:nvr510_firmware:*:*:*:*:*:*:*:*
<= 15.00.19CPE matchmatch criteria
cpe:2.3:o:yamaha:nvr700w_firmware:*:*:*:*:*:*:*:*
<= 14.01.38CPE matchmatch criteria
cpe:2.3:o:yamaha:rtx1210_firmware:*:*:*:*:*:*:*:*
<= 15.02.17CPE matchmatch criteria
cpe:2.3:o:ntt-west:biz_box_rtx830_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.7MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.1
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.93%
Probability of exploitation in next 30 days
EPSS Percentile
56.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0093 is in the 91st percentile among its peer group of 15,225 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

business.ntt-east.co.jp / topics/2021/11_09.html
MitigationVendor Advisory
jvn.jp / en/vu/JVNVU91161784/index.html
MitigationThird Party Advisory
ntt-west.co.jp / smb/kiki_info/info/211109.html
MitigationVendor Advisory
rtpro.yamaha.co.jp / RT/FAQ/Security/JVNVU91161784.html
MitigationVendor Advisory