CVE-2026-36820
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 · uneditedShenzhen Tenda Technology Co., Ltd Tenda W20E v15.11.0.6 was discovered to contain a buffer overflow in the webAuthWhiteUserInfo parameter of the formAddWebAuthWhiteUser function. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted HTTP request.
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 confidenceA buffer overflow vulnerability exists in the Tenda W20E router firmware v15.11.0.6 within the formAddWebAuthWhiteUser function's webAuthWhiteUserInfo parameter. Attackers can send specially crafted HTTP requests with oversized input to trigger the overflow, causing denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Confirm Tenda W20E router modelAccess the router admin interface or check the device label/SSH banner to verify the exact model number is W20EAffected if The device is not a Tenda W20E router, then it is not affected by this specific CVE
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Identify firmware versionLog into the router web interface and navigate to System Settings > Firmware Upgrade, or use SSH/telnet to check /proc/version or run 'cat /etc/version' or 'ver' command to retrieve the installed firmware versionAffected if The installed firmware version is v15.11.0.6 exactly, or an unpatched version within the v15.11.0.x branch prior to vendor patch
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Verify web management interface exposureCheck router firewall settings or WAN configuration to determine if the HTTP/HTTPS management port (typically 80/443) is accessible from external IP addresses or the internetAffected if The router administrative web interface is exposed to the internet or untrusted networks, making it reachable for remote attack
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Confirm formAddWebAuthWhiteUser endpoint accessibilityAttempt to access the formAddWebAuthWhiteUser function via HTTP POST to the router's web interface, typically at /goform/formAddWebAuthWhiteUser or similar endpoint, or inspect if this API handler is enabled in the firmwareAffected if The webAuthWhiteUserInfo parameter handler is enabled and accessible without additional authentication barriers
The environment is affected if it is a Tenda W20E router running firmware v15.11.0.6 with the web management interface exposed to network where remote attackers can send crafted HTTP requests to the formAddWebAuthWhiteUser endpoint.
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 dataApply vendor firmware patches when available; alternatively, implement strict input length validation and bounds checking on the webAuthWhiteUserInfo parameter in the formAddWebAuthWhiteUser function to prevent buffer overflows.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
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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-2026-36820 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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