CVE-2026-15701
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 · uneditedA weakness has been identified in Totolink NR1800X 9.1.0u.6279_B20210910. Affected by this issue is the function Form_Logout of the file /formLogout.htm of the component lighttpd. This manipulation of the argument Host causes stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks.
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 the Form_Logout function of lighttpd web server on Totolink NR1800X (firmware 9.1.0u.6279_B20210910). The vulnerability is triggered via the Host argument in /formLogout.htm, allowing remote attackers to potentially execute arbitrary code due to improper bounds checking.
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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 device modelAccess the router's web interface or check the device label/metadata to confirm the model is Totolink NR1800XAffected if The device is a Totolink NR1800X router
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Check the installed firmware versionLog into the router admin panel (typically at 192.168.1.1) and navigate to System Status or Firmware Upgrade section to view the current firmware version, or use the router's command line if accessibleAffected if The firmware version is 9.1.0u.6279_B20210910 (exact match)
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Confirm lighttpd web server is runningCheck if the router's web management interface is accessible on the default HTTP/HTTPS ports (80/443) - the vulnerability exists in the lighttpd service that serves /formLogout.htmAffected if The lighttpd web server is running and responding to HTTP requests on the router
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Verify the vulnerable endpoint existsAttempt to access the URL path /formLogout.htm on the router's web server (e.g., http://<router-ip>/formLogout.htm) to confirm the endpoint is presentAffected if The /formLogout.htm endpoint returns a valid HTTP response (200 or similar)
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Check for remote management exposureDetermine if the router's web interface is accessible from external networks (not just LAN) - check router firewall settings, WAN access policies, or port forwarding rules that expose port 80/443 to the internetAffected if The router's web management interface is accessible from WAN/external networks
You are affected if you have a Totolink NR1800X router running firmware version 9.1.0u.6279_B20210910 with the lighttpd web server and /formLogout.htm endpoint accessible, especially from remote networks.
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 dataThis is an end-of-life router with no vendor patch available; implement network segmentation to isolate the device, disable remote management interfaces, and strongly consider replacing with a currently supported device.
- Consultation4.0 h
- Implementation8.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-15701 — 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-2026-15701 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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