CVE-2021-20858
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 · uneditedCross-site scripting vulnerability in ELECOM LAN router WRC-2533GHBK-I firmware v1.20 and prior allows a remote authenticated attacker to inject an arbitrary script 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 confidenceCross-site scripting vulnerability in ELECOM WRC-2533GHBK-I router web interface allows authenticated attackers to inject arbitrary JavaScript or HTML into the router's management pages. The attack requires prior authentication, suggesting the XSS payload could be stored in configuration settings or reflected through specific web requests.
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<= 1.20CVSS 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
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 the router modelAccess the router's web administration interface (typically at 192.168.1.1 or 192.168.0.1) and look for the device model name in the status or system information page, or physically inspect the device labelAffected if The model displayed or labeled is ELECOM WRC-2533GHBK-I
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Check the installed firmware versionIn the router's web interface, navigate to the firmware or system information page and locate the firmware version number displayedAffected if The firmware version is 1.20 or lower (any version <= 1.20)
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Confirm web management interface is accessibleAttempt to reach the router's web interface from a browser on a connected deviceAffected if The administrative web interface responds and accepts login credentials
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Check if remote/remote management is enabledIn the router's web interface, look for a setting commonly labeled 'Remote Management', 'Remote Access', or 'WAN Access' in the administration or security settingsAffected if Remote management is enabled, allowing access from external networks
You are affected if you have an ELECOM WRC-2533GHBK-I router running firmware version 1.20 or lower with the web management interface accessible.
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 ELECOM WRC-2533GHBK-I firmware to version v1.21 or later. If update unavailable, restrict administrative web interface access to trusted IP addresses only and disable remote management if not required.
- 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-2021-20858 — 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-2021-20858 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
- No spam, self-promotion, credentials, or personal data