CVE-2020-5531
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 Electric MELSEC C Controller Module and MELIPC Series MI5000 MELSEC-Q Series C Controller Module(Q24DHCCPU-V, Q24DHCCPU-VG User Ethernet port (CH1, CH2): First 5 digits of serial number 21121 or before), MELSEC iQ-R Series C Controller Module / C Intelligent Function Module(R12CCPU-V Ethernet port (CH1, CH2): First 2 digits of serial number 11 or before, and RD55UP06-V Ethernet port: First 2 digits of serial number 08 or before), and MELIPC Series MI5000(MI5122-VW Ethernet port (CH1): First 2 digits of serial number 03 or before, or the firmware version 03 or before) allow remote attackers to cause a denial of service and/or malware being executed via unspecified vectors.
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 confidenceThis is a critical remote code execution and denial of service vulnerability in Mitsubishi Electric MELSEC C Controller modules and MELIPC Series devices. The flaw resides in the user Ethernet ports (CH1, CH2) of affected controllers, allowing remote attackers to execute arbitrary code or cause service disruption. The vulnerability affects specific serial number ranges and firmware versions across multiple controller models.
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<= 03<= 21121<= 21121<= 11<= 08CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the MELSEC controller modelLocate the model number label on the C Controller module or MELIPC device. Common identifiers include Mi5122, Q24dhccpu, R12ccpu, or Rd55up06 printed on the hardware unit or listed in the device configuration software.Affected if The model matches one of: Mi5122 Vw, Q24dhccpu V, Q24dhccpu Vg, R12ccpu V, or Rd55up06 V.
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Check the installed firmware versionAccess the controller via Mitsubishi configuration software or the device web interface and retrieve the firmware version information. The version is typically displayed in system information or device properties.Affected if Firmware version is at or below: 03 for Mi5122 Vw, 21121 for Q24dhccpu V or Q24dhccpu Vg, 11 for R12ccpu V, or 08 for Rd55up06 V.
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Verify if user Ethernet ports CH1 or CH2 are enabledCheck the controller network configuration settings via the engineering tool or web interface to confirm whether user Ethernet ports (CH1, CH2) have been configured and activated for network communication.Affected if Either user Ethernet port CH1 or CH2 is configured and active on the device.
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Assess network exposure of Ethernet portsReview firewall rules and network segmentation to determine if the device Ethernet ports are accessible from untrusted networks or the internet. Check for direct connections to external networks without intermediate protection.Affected if The user Ethernet ports are reachable from untrusted or external networks without adequate network segmentation.
A user is affected if they have one of the listed controller models with firmware at or below the specified version AND have user Ethernet ports CH1 or CH2 enabled AND those ports are exposed to untrusted networks.
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 dataNetwork segmentation and firewall controls should be implemented to limit exposure of affected Ethernet ports to untrusted networks. Organizations should contact Mitsubishi Electric for patched firmware and apply updates during planned maintenance windows.
- Consultation8.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-5531 — 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-2020-5531 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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