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423 41w\/ac FirmwareOperating system · Furukawa

CVE-2021-37384

CRITICAL · 9.8 CVSS v3.1 Published 2023-07-17
Fix available
A fix is available. Upgrade to 1.2.0 / 1.4.0 or later.
See remediation →
100/100
Remediation priority · Urgent
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
RCE (Remote Code Execution) vulnerability was found in some Furukawa ONU models, this vulnerability allows remote unauthenticated users to send arbitrary commands to the device via web interface.

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

A critical RCE vulnerability in Furukawa ONU (Optical Network Unit) devices allows remote unauthenticated attackers to execute arbitrary commands on the device through the web management interface. The lack of authentication combined with the ability to inject and execute commands makes this highly severe.

MitigationIsolate affected ONU devices behind restrictive firewall rules to block external access to the web management interface; contact Furukawa for firmware updates; disable remote web management if not operationally required.

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
423 41w\/ac FirmwareOperating system
Affected:< 1.2.0
Ld421 21w FirmwareOperating system
Affected:< 1.5.0
Ld420 10r FirmwareOperating system
Affected:< 1.4.0
Ld421 21wv FirmwareOperating system
Affected:< 1.5.0

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 checks

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

  1. Identify the device model
    Access the device web interface or use SNMP/SSH to query the device model identifier. Look for 'Furukawa 423 41w/ac', 'Ld421 21w', 'Ld420 10r', or 'Ld421 21wv' in the system information page or device label.
    Affected if The device model matches one of the four affected models listed in the CVE.
  2. Check the installed firmware version
    Navigate to the web management interface system status or firmware information page. Alternatively, use the command line interface (if accessible) to query the firmware version, typically with a command like 'show version' or by inspecting the web interface footer/status panel.
    Affected if The firmware version is lower than 1.2.0 for 423 41w/ac, lower than 1.5.0 for Ld421 21w or Ld421 21wv, or lower than 1.4.0 for Ld420 10r.
  3. Verify the web management interface is accessible
    Attempt to access the device web interface from a remote location using HTTP/HTTPS to the device IP address. Check if the login page or management interface responds without requiring authentication.
    Affected if The web management interface is reachable from a network segment where untrusted users could access it, especially from external networks.
  4. Confirm remote management is enabled
    In the web interface, navigate to the Administration, Management, or Network Settings section. Look for settings related to 'Remote Management', 'HTTP/HTTPS Access', or 'Web Interface Access' and verify whether remote IP addresses are permitted.
    Affected if Remote management is enabled and allows access from untrusted networks, which enables the unauthenticated attack vector described in the CVE.

A defender is affected if they have a Furukawa ONU device matching one of the four models, running firmware below the specified version thresholds, with the web management interface exposed to untrusted network segments.

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.

dbcve · scoped
Upgrade available Upgrade to 1.2.0 / 1.4.0 / 1.5.0 or later
Fixed in 1.2.01.4.01.5.0
Interim mitigation

Isolate affected ONU devices behind restrictive firewall rules to block external access to the web management interface; contact Furukawa for firmware updates; disable remote web management if not operationally required.

Recommended fix Moderate confidence

Firmware 1.2.0 for 423 41w/ac | Firmware 1.5.0 for Ld421 21w/Ld421 21wv | Firmware 1.4.0 for Ld420 10r

  1. Identify the specific Furukawa ONU model (423 41w/ac, Ld421 21w, Ld420 10r, or Ld421 21wv) in your environment
  2. Access the device's web administration interface or CLI
  3. Navigate to the firmware update section
  4. Obtain the appropriate firmware version from the official Furukawa source: 1.2.0 for 423 41w/ac, 1.5.0 for Ld421 21w and Ld421 21wv, or 1.4.0 for Ld420 10r
  5. Upload and apply the firmware update
  6. Verify the device is operational after the update
  7. Confirm the new firmware version is running

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in 423 41w\/ac Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-37384 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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