How severe is CVE-2021-20731?

CVE-2021-20731 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20731 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20731?

CVE-2021-20731 primarily affects Buffalo Wsr-1166dhp4 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20731?

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

When was CVE-2021-20731 published?

CVE-2021-20731 was published on 2021-06-09 and last updated on 2026-06-17.

CVE-2021-20731

CVE-2021-20731 is a high-severity vulnerability in Buffalo Wsr-1166dhp4 Firmware with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 8.3
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Buffalo Wsr-1166dhp4 Firmware
Published: 2021-06-09
Last modified: 2026-06-17

Description

WSR-1166DHP3 firmware Ver.1.16 and prior and WSR-1166DHP4 firmware Ver.1.02 and prior allow an attacker to execute arbitrary OS commands with root privileges via unspecified vectors.

Frequently asked questions

What is CVE-2021-20731?: WSR-1166DHP3 firmware Ver.1.16 and prior and WSR-1166DHP4 firmware Ver.1.02 and prior allow an attacker to execute arbitrary OS commands with root privileges via unspecified vectors.
How severe is CVE-2021-20731?: CVE-2021-20731 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20731 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20731?: CVE-2021-20731 primarily affects Buffalo Wsr-1166dhp4 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20731?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-20731 published?: CVE-2021-20731 was published on 2021-06-09 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:buffalo:wsr-1166dhp4_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:buffalo:wsr-1166dhp3_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Buffalo Wsr-1166dhp4 Firmware

CVE-2021-20730 — Medium (CVSS 4.3): Improper access control vulnerability in WSR-1166DHP3 firmware Ver.1.16 and prior and WSR-1166DHP4 firmware Ver.1.02…

All CVEs affecting Buffalo Wsr-1166dhp4 Firmware →

Other CWE-78 (OS Command Injection) vulnerabilities

CVE-2026-56004 — Critical (CVSS 10.0): A shellcode injection in the mercurial handler of the obs tar_scm source service before version 0.12.4 could be used by…
CVE-2026-56415 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability within the debug.pl script that is…
CVE-2026-56413 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability in the ms_service.pl service, which listens…
CVE-2026-49869 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in…
CVE-2026-49261 — Critical (CVSS 10.0): MariaDB server is a community developed fork of MySQL server. Versions 10.6.1 through 10.6.26, 10.11.1 through…
CVE-2026-10520 — Critical (CVSS 10.0): An OS Command Injection vulnerability in Ivanti Sentry before the R10.5.2, R10.6.2 and R10.7.1 versions allows a…

Browse all CWE-78 (OS Command Injection) vulnerabilities →