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Pc10g Cpu Tcc 6353 FirmwareOperating system · Jtekt

CVE-2021-27458

HIGH · 7.5 CVSS v3.1 Published 2021-04-19
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
If Ethernet communication of the JTEKT Corporation TOYOPUC product series’ (TOYOPUC-PC10 Series: PC10G-CPU TCC-6353: All versions, PC10GE TCC-6464: All versions, PC10P TCC-6372: All versions, PC10P-DP TCC-6726: All versions, PC10P-DP-IO TCC-6752: All versions, PC10B-P TCC-6373: All versions, PC10B TCC-1021: All versions, PC10B-E/C TCU-6521: All versions, PC10E TCC-4737: All versions; TOYOPUC-Plus Series: Plus CPU TCC-6740: All versions, Plus EX TCU-6741: All versions, Plus EX2 TCU-6858: All versions, Plus EFR TCU-6743: All versions, Plus EFR2 TCU-6859: All versions, Plus 2P-EFR TCU-6929: All versions, Plus BUS-EX TCU-6900: All versions; TOYOPUC-PC3J/PC2J Series: FL/ET-T-V2H THU-6289: All versions, 2PORT-EFR THU-6404: All versions) are left in an open state by an attacker, Ethernet communications cannot be established with other devices, depending on the settings of the link parameters.

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

This is a denial-of-service vulnerability in JTEKT TOYOPUC PLCs where an attacker can leave Ethernet communications in an 'open state,' preventing legitimate Ethernet communications from being established with other devices. The attack's effectiveness depends on the link parameter settings of the affected device.

MitigationImplement network segmentation and firewall rules to restrict unauthorized access to the TOYOPUC devices' Ethernet interfaces, and deploy network monitoring to detect anomalous connection states that could indicate this DoS condition.

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
Pc10g Cpu Tcc 6353 FirmwareOperating system
Affected:all versions
Pc10ge Tcc 6464 FirmwareOperating system
Affected:all versions
Pc10p Tcc 6372 FirmwareOperating system
Affected:all versions
Pc10p Dp Tcc 6726 FirmwareOperating system
Affected:all versions
Pc10p Dp Io Tcc 6752 FirmwareOperating system
Affected:all versions
Pc10b P Tcc 6373 FirmwareOperating system
Affected:all versions
Pc10b Tcc 1021 FirmwareOperating system
Affected:all versions
Pc10b E\/c Tcu 6521 FirmwareOperating system
Affected:all versions

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 PLC model in your environment
    Locate and inspect the PLC hardware nameplate or use the vendor's configuration software to determine the exact model number. Match against the affected models: Pc10g Cpu Tcc 6353, Pc10ge Tcc 6464, Pc10p Tcc 6372, Pc10p Dp Tcc 6726, Pc10p Dp Io Tcc 6752, Pc10b P Tcc 6373, Pc10b Tcc 1021, or Pc10b E/c Tcu 6521.
    Affected if The installed device is any of the JTEKT TOYOPUC models listed in the affected products.
  2. Verify the firmware version
    Connect to the PLC using the TOYOPUC programming software and retrieve the firmware version information from the CPU module properties or system information screen.
    Affected if The device is one of the affected models regardless of firmware version, as all versions are vulnerable.
  3. Check Ethernet link parameter settings
    Access the PLC configuration software and navigate to the Ethernet or link parameter configuration settings. Look for parameters that control the Ethernet communication initialization and connection behavior.
    Affected if The link parameters allow Ethernet communications to be left in an 'open state' after an unauthorized access attempt, which is the condition that enables the DoS.
  4. Monitor for connection failures
    Attempt to establish Ethernet communications with the PLC from legitimate devices and other network hosts. Observe whether connections fail or hang in an 'open' state.
    Affected if Legitimate Ethernet communications cannot be established or remain stuck in an open state, indicating the DoS condition may be present.

You are affected if you have any of the listed JTEKT TOYOPUC PLC models in your environment and observe unexplained failures of Ethernet communications or connections stuck in an open state.

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

Implement network segmentation and firewall rules to restrict unauthorized access to the TOYOPUC devices' Ethernet interfaces, and deploy network monitoring to detect anomalous connection states that could indicate this DoS condition.

Fix this in Pc10g Cpu Tcc 6353 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,380
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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-2021-27458 in production — separate from our analysis above.

No notes yet

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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