CVE-2020-16850
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 · uneditedMitsubishi MELSEC iQ-R Series PLCs with firmware 49 allow an unauthenticated attacker to halt the industrial process by sending a crafted packet over the network. This denial of service attack exposes Improper Input Validation. After halting, physical access to the PLC is required in order to restore production, and the device state is lost. This is related to R04CPU, RJ71GF11-T2, R04CPU, and RJ71GF11-T2.
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 confidenceMitsubishi MELSEC iQ-R Series PLCs (R04CPU, RJ71GF11-T2) with firmware 49 contain an improper input validation vulnerability that allows unauthenticated remote attackers to send specially crafted packets over the network, causing the PLC to halt the industrial process. Recovery requires physical access to the PLC, resulting in complete loss of device state.
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<= 20<= 20<= 20<= 52<= 52<= 52<= 52<= 52CVSS 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 MELSEC iQ-R PLC models on the networkInventory all PLC devices on the network and note the model numbers (R00CPU, R01CPU, R02CPU, R04CPU, R08CPU, R16CPU, R32CPU, R120CPU). Use network scans, asset discovery tools, or consult engineering documentation.Affected if Any MELSEC iQ-R Series PLC model (R00CPU, R01CPU, R02CPU, R04CPU, R08CPU, R16CPU, R32CPU, R120CPU) is present on the network
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Determine the firmware version of each iQ-R PLCAccess the PLC via GX Works3 engineering software or check the CPU unit front panel display for the firmware version. Navigate to the CPU module properties or system information in the programming software.Affected if Firmware version is <= 20 for R00CPU/R01CPU/R02CPU, or <= 52 for R04CPU/R08CPU/R16CPU/R32CPU/R120CPU
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Verify network accessibility of affected PLCsCheck if the PLC has an active Ethernet or MELSEC iQ-R network interface configured and is reachable on the network. Confirm the PLC IP address is accessible via ping or network scan.Affected if The affected PLC model with vulnerable firmware is network-accessible from any untrusted segment
You are affected if you have any MELSEC iQ-R Series PLC (R00CPU, R01CPU, R02CPU, R04CPU, R08CPU, R16CPU, R32CPU, or R120CPU) running firmware at or below the specified version limits and that PLC is reachable on your network.
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 and firewalls to restrict unauthorized access to the PLC network, and monitor for anomalous network traffic. Additionally, check with Mitsubishi for available firmware updates that may address this vulnerability.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA8.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-16850 — 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-2020-16850 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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