CVE-2026-36791
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 O3v3 v1.0.0.5 was discovered to contain a stack overflow in the save_list_data parameter of the formSetCfm 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 · moderate confidenceA stack overflow vulnerability exists in the Tenda O3v3 v1.0.0.5 router firmware in the formSetCfm function's save_list_data parameter. Attackers can send a crafted HTTP request with excessively long data to overflow the stack, causing the device to crash and result in 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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Identify the router modelAccess the router's web interface or check the device label to confirm it is a Tenda O3v3 router. Alternatively, inspect the HTTP server banner or SNMP information if accessible.Affected if The device is a Tenda O3v3 router
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Check the firmware versionLog into the router web interface and navigate to the System Status or Firmware Upgrade page to view the installed firmware version. Alternatively, use TFTP or a similar method to extract and inspect the firmware file directly.Affected if The firmware version is v1.0.0.5
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Verify the web management interface is enabledAttempt to access the router's HTTP/HTTPS web interface (typically at the default gateway IP) to confirm it is reachable. Check if port 80 or 443 is open.Affected if The web interface is accessible and the router is reachable on the network
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Confirm the vulnerable parameter endpoint existsSend a crafted HTTP POST request to the formSetCfm function endpoint (commonly /goform/ or /cgi/ on Tenda routers) with a save_list_data parameter. Use a tool like curl: curl -X POST http://<router_ip>/goform/formSetCfm -d "save_list_data=test"Affected if The router responds to requests with a save_list_data parameter (indicating the function exists)
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Check for input length validationSend an HTTP POST request with an unusually long string in the save_list_data parameter (e.g., 2000+ characters) and observe the router response. A vulnerable device may crash, become unresponsive, or exhibit abnormal behavior.Affected if The router accepts arbitrarily long input without rejecting it, or becomes unresponsive after sending a long string
You are affected if you have a Tenda O3v3 router running firmware v1.0.0.5 with an accessible web interface that accepts the save_list_data parameter without proper bounds checking.
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 dataUntil an official firmware patch is available, restrict administrative web interface access to trusted networks or IP addresses using firewall rules. Consider disabling remote management if not required.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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-2026-36791 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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