CVE-2021-3512
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceImproper access control in Buffalo broadband routers allows remote unauthenticated attackers to bypass authentication and enable the telnet service, then execute arbitrary OS commands with root privileges via unspecified vectors.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 2.00< 1.84< 2.00< 2.00< 2.00< 1.87< 2.00< 1.87CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify router modelLocate the Buffalo router model number on the device label or administrative web interface (typically at http://192.168.1.1 or similar). Common model identifiers include Bhr-4grv, Dwr-Hp-G300nh, Hw-450hp-Zwe, Whr-300hp, Whr-300, Whr-G301n, Whr-Hp-G300n, Whr-Hp-Gn.Affected if Router is any of the eight Buffalo models listed in affected products
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Check installed firmware versionAccess the router administrative interface and navigate to the System or Administration section to view the firmware version. Alternatively, some models may expose version information via the web interface or by making a request to the device.Affected if Firmware version is below the threshold for your specific model (Bhr-4grv < 2.00, Dwr-Hp-G300nh < 1.84, Hw-450hp-Zwe < 2.00, Whr-300hp < 2.00, Whr-300 < 2.00, Whr-G301n < 1.87, Whr-Hp-G300n < 2.00, Whr-Hp-Gn < 1.87)
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Verify telnet service statusAttempt to connect to the router on telnet port 23 (e.g., using telnet or nc commands) from an internal network host. Check if the port responds or accepts connections.Affected if Telnet service is unexpectedly enabled and accessible (especially from external/network perspectives)
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Inspect for unauthorized configuration changesReview router configuration for any unexpected changes to service settings, particularly telnet, remote management, or firewall rules. Log into the admin interface and compare current settings against known-good baselines if available.Affected if Telnet or remote access services have been enabled without legitimate administrative action
The environment is affected if the router is one of the eight Buffalo models listed and the installed firmware version falls below the specified threshold for that model, or if unauthorized telnet access is detected.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.841.872.00
Update firmware to versions newer than those listed (1.99, 1.83, 1.86, 1.75, 1.85, 1.89, 3.32, 3.38, 3.39, 3.13 depending on model). If update unavailable, disable telnet access at network perimeter and monitor for unauthorized telnet connections.
Upgrade to the next firmware revision after the vulnerable version (e.g., BHR-4GRV to 2.00, DWR-HP-G300NH to 1.84, WHR-G301N to 1.87, WHR-HP-GN to 1.87). Check Buffalo's official support pages for exact patched releases.
- 1. Identify the exact Buffalo router model from the affected products list
- 2. Access the router's web administration interface or Buffalo's support website
- 3. Navigate to the firmware update section for your specific model
- 4. Download the firmware version that is one increment higher than the vulnerable version listed
- 5. Upload and apply the firmware update following the on-screen instructions
- 6. After reboot, verify the firmware version has been updated successfully
- 7. Ensure telnet is disabled by default after update (if applicable)
- 8. Consider changing administrative credentials as a precautionary measure
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3512 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-3512 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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