Plc Cj FirmwareOperating system · Omron

CVE-2019-18259

CRITICAL · 9.8 CVSS v3.1 Published 2019-12-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
In Omron PLC CJ series, all versions and Omron PLC CS series, all versions, an attacker could spoof arbitrary messages or execute commands.

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 vulnerability exists in the Omron CJ and CS series PLCs where an attacker on the network can spoof arbitrary messages or execute commands, likely due to missing authentication or message validation in the PLC communication protocol. The CVSS 9.8 indicates this is remotely exploitable with no user interaction required.

MitigationIsolate PLCs behind industrial firewalls or network segmentation; restrict network access to trusted sources only; implement DMZ architectures for SCADA/ICS environments.

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
Plc Cj FirmwareOperating system
Affected:all versions
Plc Cs 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
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 Omron CJ or CS series PLCs on the network
    Scan the network for devices with Omron-specific vendor identifiers or check PLC hardware models directly. Use network scanning tools or consult asset inventories to locate devices with model numbers starting with CJ or CS.
    Affected if Any Omron CJ or CS series PLC is present on the network
  2. Verify PLC firmware version
    Access the PLC via its programming software (such as CX-Programmer) or check the device directly to confirm the firmware version is any version.
    Affected if Firmware version is any version (all versions are affected)
  3. Check if PLC communication ports are network-accessible
    Scan for open ports commonly used by Omron PLCs (typically UDP port 9600 for FINS protocol). Use network scanning tools to determine if these ports respond to external network requests.
    Affected if The PLC protocol ports (e.g., UDP 9600) are exposed to untrusted networks or accessible from beyond the local control system segment

If Omron CJ or CS series PLCs exist with their PLC protocol ports accessible from the network, the environment is affected by this vulnerability.

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

Isolate PLCs behind industrial firewalls or network segmentation; restrict network access to trusted sources only; implement DMZ architectures for SCADA/ICS environments.

Fix this in Plc Cj Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
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Scan for this in your stack

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dbcve dependency scanner

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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-2019-18259 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