CVE-2020-6986
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 · uneditedIn all versions of Omron PLC CJ Series, an attacker can send a series of specific data packets within a short period, causing a service error on the PLC Ethernet module, which in turn causes a PLC service denied result.
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 confidenceA denial of service vulnerability exists in the Ethernet communication module of all Omron CJ Series PLCs. An unauthenticated remote attacker can send specially crafted data packets in rapid succession to trigger a service error, causing the PLC to become unresponsive and unable to process legitimate communications.
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 dataall versionsall versionsCVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify Omron CJ Series PLCs in your environmentReview your industrial control system (ICS) asset inventory, network diagrams, or physically inspect PLC hardware labels to determine if CJ1 or CJ2 series PLCs are deployedAffected if Any CJ1 or CJ2 Omron PLC is present in the environment
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Confirm Ethernet communication module is enabledAccess the PLC programming software (e.g., CX-Programmer) or PLC configuration menus and verify if the Ethernet communication module (built-in Ethernet port or Ethernet unit) is configured and activeAffected if Ethernet communication module is enabled and the PLC is networked
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Assess network exposure of the PLCReview firewall rules, network segmentation, and access control lists to determine if the PLC Ethernet port is reachable from untrusted networks or the internetAffected if PLC is directly accessible from untrusted or external networks without firewall protection
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Check for PLC responsiveness issuesPing the PLC IP address or attempt to connect via CX-Programmer to verify if the PLC responds normally to legitimate communication attemptsAffected if PLC fails to respond to normal communications or shows repeated communication timeouts
If you have Omron CJ1 or CJ2 PLCs with Ethernet enabled and they are accessible from untrusted networks, your environment is affected by this CVE and could be exploited for denial of service.
Generated from the published advisory. Verify against your own configuration.
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 dataImplement network segmentation to isolate PLCs from untrusted networks, deploy rate-limiting or firewall rules on network perimeter devices to block malicious packet floods, and monitor for unusual traffic patterns. Since all versions are affected, contact Omron for firmware updates if available.
- Consultation8.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-6986 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-6986 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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