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Fx3u Enet FirmwareOperating system · Mitsubishielectric

CVE-2021-20613

HIGH · 7.5 CVSS v3.1 Published 2022-01-14
Fix available
A fix is available. Upgrade to after 1.16 or later.
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
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.

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

Improper initialization vulnerability in the Ethernet communication module of Mitsubishi MELSEC-F series PLCs (FX3U-ENET, FX3U-ENET-L, FX3U-ENET-P502) allows remote unauthenticated attackers to send specially crafted packets causing a denial-of-service condition. The PLC control logic remains unaffected but the device requires a system reset to recover.

MitigationUpdate firmware to a version newer than 1.16. Apply network segmentation and firewall controls to limit exposure to untrusted networks as an interim measure.

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
Fx3u Enet FirmwareOperating system
Affected:<= 1.16
Fx3u Enet L FirmwareOperating system
Affected:<= 1.16
Fx3u Enet P502 FirmwareOperating system
Affected:<= 1.16

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 the Ethernet module model
    Check the product label on the hardware device or review the system configuration documentation to confirm the exact model number
    Affected if The model is not one of FX3U-ENET, FX3U-ENET-L, or FX3U-ENET-P502 (if different, the CVE does not apply)
  2. Determine the installed firmware version
    Access the module's built-in web interface or use Mitsubishi configuration software to read the firmware version field
    Affected if Firmware version is 1.16 or lower (versions 1.17 and above are not affected)
  3. Confirm the Ethernet communication function is configured
    Check the PLC program and module configuration to verify that the Ethernet communication module is enabled and assigned to a network
    Affected if The Ethernet module is active and connected to a network (the vulnerability requires the module to be initialized and operational)

The device is affected if it is an FX3U-ENET, FX3U-ENET-L, or FX3U-ENET-P502 module with firmware version 1.16 or lower, and the Ethernet communication function is 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.

dbcve · scoped
Upgrade available Upgrade to a release after 1.16
Interim mitigation

Update firmware to a version newer than 1.16. Apply network segmentation and firewall controls to limit exposure to untrusted networks as an interim measure.

Recommended fix Moderate confidence

Firmware version > 1.16 (contact Mitsubishi Electric for exact fixed release)

  1. Contact Mitsubishi Electric directly or visit their official support portal to obtain the firmware update for FX3U-ENET, FX3U-ENET-L, and FX3U-ENET-P502 modules
  2. Request the specific firmware version that addresses CVE-2021-20613 (the fixed release after version 1.16)
  3. Follow Mitsubishi Electric's firmware update procedure documented in the product manual for your specific ENET module
  4. After updating firmware, verify that the communication function operates normally
  5. Implement network segmentation to limit exposure of the PLC communication interfaces to untrusted networks as an additional protective measure
Caveat Firmware updates to industrial devices should be tested in a non-production environment first; verify compatibility with your PLC program and communication settings

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

Fix this in Fx3u Enet Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,820
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,912.

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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-2021-20613 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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