CVE-2021-20853
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 · uneditedELECOM LAN routers (WRH-733GBK firmware v1.02.9 and prior and WRH-733GWH firmware v1.02.9 and prior) allows a network-adjacent attacker with an administrator privilege to execute arbitrary OS commands 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 confidenceELECOM WRH-733GBK and WRH-733GWH LAN routers firmware v1.02.9 and prior contain a vulnerability allowing a network-adjacent attacker with administrator privileges to execute arbitrary OS commands. The specific attack vector is unspecified in the advisory, but it likely represents a command injection or similar injection flaw in the router's web management interface.
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<= 1.02.9<= 1.02.9CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:H/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 the router modelLocate the physical device or access the web management interface and confirm the model number is WRH-733GBK or WRH-733GWH. Check the product label on the device bottom or the admin panel for the exact model designation.Affected if The device is an ELECOM WRH-733GBK or WRH-733GWH model router.
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Check installed firmware versionAccess the router web management interface, typically at 192.168.1.1 or similar, and navigate to the System or Firmware section to view the currently installed firmware version. The version is usually displayed on the status or administration page.Affected if The installed firmware version is 1.02.9 or any version prior to 1.02.9.
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Verify web management interface is enabledCheck the router administration settings to confirm the web-based management interface is enabled. Look for HTTP/HTTPS admin access settings in the router configuration.Affected if The web management interface is accessible and enabled on the network.
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Confirm administrator access statusDetermine if an administrator account exists and is configured on the router. Check the user accounts section in the router admin panel to see if administrative privileges are set.Affected if An administrator account is configured and accessible, making the command injection exploit possible.
A user is affected if they own an ELECOM WRH-733GBK or WRH-733GWH router running firmware version 1.02.9 or earlier with the web management interface accessible and an administrator account configured.
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 router firmware to v1.03 or later if available from ELECOM. If no patch is available, consider replacing the device with a currently supported model or implement network segmentation to restrict administrative access to trusted networks only.
- 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-2021-20853 — 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-2021-20853 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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- 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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