CVE-2021-3512

Improper access control vulnerability in Buffalo broadband routers (BHR-4GRV firmware Ver.1.99...

8.8 High

Improper access control vulnerability in Buffalo broadband routers (BHR-4GRV firmware Ver.1.99 and prior, DWR-HP-G300NH firmware Ver.1.83 and prior, HW-450HP-ZWE firmware Ver.1.99 and prior, WHR-300HP firmware Ver.1.99 and prior, WHR-300 firmware Ver.1.99 and prior, WHR-G301N firmware Ver.1.86 and prior, WHR-HP-G300N firmware Ver.1.99 and prior, WHR-HP-GN firmware Ver.1.86 and prior, WPL-05G300 firmware Ver.1.87 and prior, WZR-450HP-CWT firmware Ver.1.99 and prior, WZR-450HP-UB firmware Ver.1.99 and prior, WZR-HP-AG300H firmware Ver.1.75 and prior, WZR-HP-G300NH firmware Ver.1.83 and prior, WZR-HP-G301NH firmware Ver.1.83 and prior, WZR-HP-G302H firmware Ver.1.85 and prior, WZR-HP-G450H firmware Ver.1.89 and prior, WZR-300HP firmware Ver.1.99 and prior, WZR-450HP firmware Ver.1.99 and prior, WZR-600DHP firmware Ver.1.99 and prior, WZR-D1100H firmware Ver.1.99 and prior, FS-HP-G300N firmware Ver.3.32 and prior, FS-600DHP firmware Ver.3.38 and prior, FS-R600DHP firmware Ver.3.39 and prior, and FS-G300N firmware Ver.3.13 and prior) allows remote unauthenticated attackers to bypass access restriction and to start telnet service and execute arbitrary OS commands with root privileges via unspecified vectors.

Attack profile

How easy it is to exploit

Attack vector: Adjacent network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.86%Down 0.5 points since Apr 28, 2021

What each source reports

NVD Score used 8.8

Record: CVE-2021-3512
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 8.3 HighAV:A/AC:L/Au:N/C:C/I:C/A:C
Updated: 2026-11-02

CVE List No score

Record: CVE-2021-3512
Updated: 2026-11-02

EUVDEUVD-2021-26831 No score

Record: EUVD-2021-26831
Updated: 2026-11-03

GitHub AdvisoriesGHSA-m7x4-xmjq-8hxp 8.8

Improper access control vulnerability in Buffalo broadband routers (BHR-4GRV firmware Ver.1.99...

Record: GHSA-m7x4-xmjq-8hxp
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-863
Updated: 2026-11-02

Affected products

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History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-3512 is a high vulnerability (CVSS 8.8) in Buffalo Bhr-4grv Firmware, published April 28, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.86%, the 58th percentile. No source names a fixed version.