CVE-2021-20731
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 · uneditedWSR-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.
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 · moderate confidenceMultiple Buffalo WSR-1166DHP router models contain an OS command injection vulnerability allowing unauthenticated attackers to execute arbitrary commands with root privileges. The specific attack vector is not detailed in the advisory.
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<= 1.02<= 1.16CVSS 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 modelAccess the router administrative web interface and locate the device information or status page, or check the product label on the device itselfAffected if The model is Buffalo WSR-1166DHP3 or WSR-1166DHP4
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Check installed firmware versionIn the router web UI, navigate to the Administration or System section to view the firmware version. Alternatively, access the router via CLI if available and check the firmware version.Affected if The firmware version displayed is at or below 1.16 for WSR-1166DHP3, or at or below 1.02 for WSR-1166DHP4
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Compare version against affected rangesDocument the exact firmware version number found and compare it to the affected ranges: WSR-1166DHP3 <= 1.16, WSR-1166DHP4 <= 1.02Affected if The installed version falls within or below these thresholds, indicating the vulnerable firmware is in use
If the device is a WSR-1166DHP3 or WSR-1166DHP4 model running firmware at or below the affected version thresholds, the environment is vulnerable to CVE-2021-20731.
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 · scopedUpdate router firmware to a version beyond 1.16 for WSR-1166DHP3 and beyond 1.02 for WSR-1166DHP4. If updates are unavailable, restrict administrative interface exposure to trusted networks only.
WSR-1166DHP3: firmware Ver.1.17 or later; WSR-1166DHP4: firmware Ver.1.03 or later
- 1. Identify the exact model number of your Buffalo WSR router (WSR-1166DHP3 or WSR-1166DHP4)
- 2. Access the router's web administration interface via browser at the default IP (typically 192.168.1.1)
- 3. Navigate to the Administration or System settings section
- 4. Locate the firmware update option
- 5. Download the latest firmware version from Buffalo's official support website (www.buffalo.jp) for your specific model
- 6. Upload and apply the firmware update through the router's web interface
- 7. After reboot, verify the firmware version has been updated to a version newer than the vulnerable release
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20731 — 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-2021-20731 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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