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CVE-2021-20716

31
FAUCET Score

CVE-2021-20716 describes a critical vulnerability in numerous Buffalo network devices, including various BHR, FS, WBR, WHR, WLA, WLI, WVR, and WZR series firmware versions prior to their respective patches. This hidden functionality allows a remote, unauthenticated attacker to enable a debug option, leading to arbitrary code execution, OS command execution, configuration changes, and denial-of-service conditions. With a CVSS score of 9.8 (Critical), the vulnerability is easily exploitable over the network with no user interaction or privileges required, posing a significant risk of complete compromise. While not listed on CISA KEV and lacking public exploit intelligence or widespread community discussion, the high FAUCET Risk Score indicates its potential severity.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.55CPE matchmatch criteria
cpe:2.3:o:buffalo:bhr-4rv_firmware:*:*:*:*:*:*:*:*
<= 2.04CPE matchmatch criteria
cpe:2.3:o:buffalo:fs-g54_firmware:*:*:*:*:*:*:*:*
<= 2.32CPE matchmatch criteria
cpe:2.3:o:buffalo:wbr2-b11_firmware:*:*:*:*:*:*:*:*
<= 2.32CPE matchmatch criteria
cpe:2.3:o:buffalo:wbr2-g54_firmware:*:*:*:*:*:*:*:*
<= 2.32CPE matchmatch criteria
cpe:2.3:o:buffalo:wbr2-g54-kd_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.18%
Probability of exploitation in next 30 days
EPSS Percentile
86.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0318 is in the 78th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

jvn.jp / en/vu/JVNVU90274525/index.html
Third Party Advisory
buffalo.jp / news/detail/20210427-02.html
Vendor Advisory