CVE-2026-41927
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 · uneditedWDR201A WiFi Extender (HW V2.1, FW LFMZX28040922V1.02) contains a stack-based buffer overflow vulnerability in the firewall.cgi and makeRequest.cgi binaries that allows unauthenticated attackers to overwrite the saved return address by sending a POST request with a Content-Length header exceeding 512 bytes. Attackers can exploit insufficient length validation in the fgets() call to achieve arbitrary code execution through return-oriented programming or return-to-libc techniques.
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 confidenceStack-based buffer overflow in WDR201A WiFi Extender's firewall.cgi and makeRequest.cgi binaries allows unauthenticated attackers to overwrite the return address via a POST request with a Content-Length header exceeding 512 bytes, due to insufficient length validation in fgets(), enabling arbitrary code execution through ROP or return-to-libc.
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
- High
- Privileges
- None
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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 device modelAccess the device web interface or check the device label/metadata for the exact model number (WDR201A WiFi Extender)Affected if The device is not a WDR201A model - not affected
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Verify affected CGI binaries existAttempt to access /cgi-bin/firewall.cgi or /cgi-bin/makeRequest.cgi on the device web server (e.g., http://<device-ip>/cgi-bin/firewall.cgi)Affected if The CGI binaries return a valid response (indicating they are present and enabled)
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Check firmware versionAccess the device administration interface and locate the firmware version information, typically under Status, System, or Firmware Upgrade sectionsAffected if The installed firmware version predates any vendor patch (compare to published fixed versions from the vendor)
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Confirm CGI handlers are enabledVerify the web server configuration or test that CGI execution is functional on the device by sending a request to any .cgi endpoint and receiving a valid responseAffected if CGI execution is enabled and the affected binaries respond to requests
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Assess network exposure of web interfaceCheck whether the device web management interface is accessible from untrusted networks ( WAN side) or verify access control lists and firewall rulesAffected if The web interface including CGI handlers is directly accessible from untrusted networks without authentication barriers
If the device is a WDR201A WiFi Extender with the firewall.cgi or makeRequest.cgi binaries accessible and the web interface is exposed, and the firmware lacks the vendor patch, the environment is affected by this buffer overflow vulnerability.
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 patch when available; temporarily restrict access to web interface or disable CGI handlers if exploit is observed.
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-41927 — 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-2026-41927 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
- No spam, self-promotion, credentials, or personal data