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Stack-based Buffer OverflowWeakness · CWE-121

CVE-2026-36779

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Shenzhen Tenda Technology Co., Ltd Tenda O3 Wireless Router v1.0.0.5(4180) was discovered to contain multiple stack overflows in the fromVirtualSer function via the puVar2, puVar1, __s2, __s1_00, and puVar3 parameters. These vulnerabilities allow 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 confidence

Stack-based buffer overflow in Tenda O3 router firmware v1.0.0.5(4180) within the fromVirtualSer function. Multiple parameters (puVar2, puVar1, __s2, __s1_00, puVar3) accept unchecked user input from HTTP requests and copy data to fixed-size stack buffers without proper length validation, allowing controlled overflow and device crash.

MitigationApply vendor firmware patch when available; until then, disable remote web management or restrict administrative interface access to trusted IPs only.

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify router model and firmware version
    Access the router's web interface and check the system status page, or use the command 'cat /proc/version' or 'nvram get firmware_version' via telnet/SSH if available
    Affected if The device is a Tenda O3 running firmware version v1.0.0.5(4180)
  2. Verify fromVirtualSer function is exposed
    Send a crafted HTTP request to the router's web interface endpoint that triggers fromVirtualSer. This is typically a form submission to /goform/ or similar endpoint that the fromVirtualSer function handles
    Affected if The router accepts HTTP requests to the endpoint that invokes fromVirtualSer and the function lacks input validation on the parameters (puVar2, puVar1, __s2, __s1_00, puVar3)
  3. Check remote management status
    Log into the router admin panel and navigate to Advanced Settings or System Settings to verify if remote web management or remote upgrade is enabled
    Affected if Remote management is enabled, exposing the vulnerable function to network attackers rather than only local LAN users

You are affected if you have a Tenda O3 router on firmware v1.0.0.5(4180) with the fromVirtualSer function accessible via HTTP and remote management enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor firmware patch when available; until then, disable remote web management or restrict administrative interface access to trusted IPs only.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-36779 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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