How severe is CVE-2021-20716?

CVE-2021-20716 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20716 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20716?

CVE-2021-20716 primarily affects Buffalo Bhr-4rv Firmware. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20716?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-20716 published?

CVE-2021-20716 was published on 2021-04-28 and last updated on 2026-06-17.

CVE-2021-20716

CVE-2021-20716 is a critical-severity vulnerability in Buffalo Bhr-4rv Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Buffalo Bhr-4rv Firmware
Published: 2021-04-28
Last modified: 2026-06-17

Description

Hidden functionality in multiple Buffalo network devices (BHR-4RV firmware Ver.2.55 and prior, FS-G54 firmware Ver.2.04 and prior, WBR2-B11 firmware Ver.2.32 and prior, WBR2-G54 firmware Ver.2.32 and prior, WBR2-G54-KD firmware Ver.2.32 and prior, WBR-B11 firmware Ver.2.23 and prior, WBR-G54 firmware Ver.2.23 and prior, WBR-G54L firmware Ver.2.20 and prior, WHR2-A54G54 firmware Ver.2.25 and prior, WHR2-G54 firmware Ver.2.23 and prior, WHR2-G54V firmware Ver.2.55 and prior, WHR3-AG54 firmware Ver.2.23 and prior, WHR-G54 firmware Ver.2.16 and prior, WHR-G54-NF firmware Ver.2.10 and prior, WLA2-G54 firmware Ver.2.24 and prior, WLA2-G54C firmware Ver.2.24 and prior, WLA-B11 firmware Ver.2.20 and prior, WLA-G54 firmware Ver.2.20 and prior, WLA-G54C firmware Ver.2.20 and prior, WLAH-A54G54 firmware Ver.2.54 and prior, WLAH-AM54G54 firmware Ver.2.54 and prior, WLAH-G54 firmware Ver.2.54 and prior, WLI2-TX1-AG54 firmware Ver.2.53 and prior, WLI2-TX1-AMG54 firmware Ver.2.53 and prior, WLI2-TX1-G54 firmware Ver.2.20 and prior, WLI3-TX1-AMG54 firmware Ver.2.53 and prior, WLI3-TX1-G54 firmware Ver.2.53 and prior, WLI-T1-B11 firmware Ver.2.20 and prior, WLI-TX1-G54 firmware Ver.2.20 and prior, WVR-G54-NF firmware Ver.2.02 and prior, WZR-G108 firmware Ver.2.41 and prior, WZR-G54 firmware Ver.2.41 and prior, WZR-HP-G54 firmware Ver.2.41 and prior, WZR-RS-G54 firmware Ver.2.55 and prior, and WZR-RS-G54HP firmware Ver.2.55 and prior) allows a remote attacker to enable the debug option and to execute arbitrary code or OS commands, change the configuration, and cause a denial of service (DoS) condition.

Frequently asked questions

What is CVE-2021-20716?: Hidden functionality in multiple Buffalo network devices (BHR-4RV firmware Ver.2.55 and prior, FS-G54 firmware Ver.2.04 and prior, WBR2-B11 firmware Ver.2.32 and prior, WBR2-G54 firmware Ver.2.32 and prior, WBR2-G54-KD firmware Ver.2.32 and prior, WBR-B11 firmware Ver.2.23 and prior, WBR-G54 firmware Ver.2.23 and prior, WBR-G54L firmware Ver.2.20 and prior, WHR2-A54G54 firmware Ver.2.25 and prior, WHR2-G54 firmware Ver.2.23 and prior, WHR2-G54V firmware Ver.2.55 and prior, WHR3-AG54 firmware Ver.2.23 and prior, WHR-G54 firmware Ver.2.16 and prior, WHR-G54-NF firmware Ver.2.10 and prior, WLA2-G54 firmware Ver.2.24 and prior, WLA2-G54C firmware Ver.2.24 and prior, WLA-B11 firmware Ver.2.20 and prior, WLA-G54 firmware Ver.2.20 and prior, WLA-G54C firmware Ver.2.20 and prior, WLAH-A54G54 firmware Ver.2.54 and prior, WLAH-AM54G54 firmware Ver.2.54 and prior, WLAH-G54 firmware Ver.2.54 and prior, WLI2-TX1-AG54 firmware Ver.2.53 and prior, WLI2-TX1-AMG54 firmware Ver.2.53 and prior, WLI2-TX1-G54 firmware Ver.2.20 and prior, WLI3-TX1-AMG54 firmware Ver.2.53 and prior, WLI3-TX1-G54 firmware Ver.2.53 and prior, WLI-T1-B11 firmware Ver.2.20 and prior, WLI-TX1-G54 firmware Ver.2.20 and prior, WVR-G54-NF firmware Ver.2.02 and prior, WZR-G108 firmware Ver.2.41 and prior, WZR-G54 firmware Ver.2.41 and prior, WZR-HP-G54 firmware Ver.2.41 and prior, WZR-RS-G54 firmware Ver.2.55 and prior, and WZR-RS-G54HP firmware Ver.2.55 and prior) allows a remote attacker to enable the debug option and to execute arbitrary code or OS commands, change the configuration, and cause a denial of service (DoS) condition.
How severe is CVE-2021-20716?: CVE-2021-20716 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20716 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20716?: CVE-2021-20716 primarily affects Buffalo Bhr-4rv Firmware. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20716?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-20716 published?: CVE-2021-20716 was published on 2021-04-28 and last updated on 2026-06-17.

References

Affected products (35)

cpe:2.3:o:buffalo:bhr-4rv_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:fs-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr2-b11_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr2-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr2-g54-kd_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr-b11_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wbr-g54l_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr2-a54g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr2-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr2-g54v_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr3-ag54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:whr-g54-nf_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wla2-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wla2-g54c_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wla-b11_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wla-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wla-g54c_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wlah-a54g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wlah-am54g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wlah-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli2-tx1-ag54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli2-tx1-amg54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli2-tx1-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli3-tx1-amg54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli3-tx1-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli-t1-b11_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wli-tx1-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wvr-g54-nf_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wzr-g108_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wzr-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wzr-hp-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wzr-rs-g54_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wzr-rs-g54hp_firmware:*:*:*:*:*:*:*:*