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I21 FirmwareOperating system · Tenda

CVE-2024-4491

HIGH · 8.8 CVSS v3.1 Published 2024-05-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
A vulnerability classified as critical was found in Tenda i21 1.0.0.14(4656). This vulnerability affects the function formGetDiagnoseInfo. The manipulation of the argument cmdinput leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-263080. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.

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 confidence

Stack-based buffer overflow in Tenda i21 router firmware 1.0.0.14(4656) in the formGetDiagnoseInfo function. The cmdinput parameter is not properly bounds-checked before being copied to a stack buffer, allowing remote attackers to overflow the stack and potentially execute arbitrary code or cause denial of service.

MitigationApply vendor firmware update if available; otherwise restrict management interface access to trusted networks and implement network segmentation to reduce attack surface exposure.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
I21 FirmwareOperating system
Affected:= 1.0.0.14\(4656\)

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

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

  1. Identify device model
    Check the router label or access the admin interface to confirm the model is Tenda I21
    Affected if Device is not a Tenda I21 router - this vulnerability only affects that specific model
  2. Check firmware version
    Access the router admin interface (typically at 192.168.0.1) and navigate to System Settings or Firmware Upgrade to view the installed firmware version, or use the command 'cat /proc/version' via telnet/SSH if available
    Affected if Firmware version is exactly 1.0.0.14(4656) - only this specific version is listed as affected
  3. Verify web management interface is accessible
    Attempt to access the router web interface on port 80/tcp from a browser
    Affected if The web management interface is exposed and accessible - the vulnerable formGetDiagnoseInfo function is accessed through this interface
  4. Confirm the vulnerable function exists
    Access the router web interface and look for diagnostic or network diagnostic features that would invoke the formGetDiagnoseInfo function, or send an HTTP request to the endpoint that handles this function (such as /goform/formGetDiagnoseInfo)
    Affected if The diagnostic feature or the formGetDiagnoseInfo endpoint is present and responds - this confirms the vulnerable code path exists
  5. Check network exposure of management interface
    Determine if the router management interface is accessible from outside the local network by testing remote IP access on port 80/tcp or performing a port scan
    Affected if The management interface is exposed to untrusted networks (WAN) rather than only accessible from LAN - this increases exploitability

You are affected if you have a Tenda I21 router running firmware version 1.0.0.14(4656) with the web management interface accessible, as the formGetDiagnoseInfo function contains the stack-based buffer overflow in the cmdinput parameter.

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 update if available; otherwise restrict management interface access to trusted networks and implement network segmentation to reduce attack surface exposure.

Fix this in I21 Firmware Scoped from the published advisory
  • Consultation6.0 h
  • Implementation32.0 h
  • Testing16.0 h
  • Review / QA8.0 h
62.0 hours of engineering $10,800
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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-2024-4491 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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