CVE-2021-20712
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 NEC Aterm WG2600HS firmware Ver1.5.1 and earlier, and Aterm WX3000HP firmware Ver1.1.2 and earlier allows a device connected to the LAN side to be accessed from the WAN side due to the defect in the IPv6 firewall function.
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 confidenceThe NEC Aterm WG2600HS and WX3000HP routers have a defect in their IPv6 firewall function that allows devices on the protected LAN side to be accessed from the WAN side. This improper access control bypasses the intended firewall isolation, potentially exposing internal network devices to external attackers via IPv6 traffic.
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<= 1.5.1<= 1.1.2CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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 admin web interface or check the physical device label to confirm the model is either Aterm WG2600HS or Aterm WX3000HP.Affected if The model is not WG2600HS or WX3000HP, then this CVE does not apply.
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Check WG2600HS firmware versionLog into the router admin interface, navigate to the status or firmware information page, and record the firmware version number.Affected if The firmware version is 1.5.1 or lower on a WG2600HS.
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Check WX3000HP firmware versionLog into the router admin interface, navigate to the status or firmware information page, and record the firmware version number.Affected if The firmware version is 1.1.2 or lower on a WX3000HP.
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Verify IPv6 is enabledIn the router admin interface, check the IPv6 or WAN settings to determine if IPv6 functionality is turned on.Affected if IPv6 is disabled on the router, the specific firewall bypass is not applicable.
The router is affected if it is a WG2600HS with firmware 1.5.1 or lower, or a WX3000HP with firmware 1.1.2 or lower, and IPv6 is enabled on the WAN interface.
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.
From vendor dataUpdate the router firmware to at least Ver1.5.2 for WG2600HS or Ver1.1.3 for WX3000HP. If immediate patching is not possible, consider disabling IPv6 on the WAN interface or implementing additional perimeter filtering.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-20712 — 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-2021-20712 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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