CVE-2024-0803
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 · uneditedInteger Overflow or Wraparound vulnerability in Mitsubishi Electric Corporation MELSEC-Q Series and MELSEC-L Series CPU modules allows a remote unauthenticated attacker to execute malicious code on a target product by sending a specially crafted packet.
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 confidenceInteger overflow vulnerability in Mitsubishi MELSEC-Q and MELSEC-L Series CPU modules allows remote unauthenticated attackers to execute arbitrary code via specially crafted network packets due to improper integer handling in the packet processing routine.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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 checksWork through these to decide whether this CVE applies to you.
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Identify MELSEC-Q or MELSEC-L PLCs on the networkScan the network for devices using MELSEC protocol (typically UDP/TCP port 5007) or identify Mitsubishi PLC model numbers via network enumeration tools or engineering station documentationAffected if MELSEC-Q or MELSEC-L Series CPU modules are present on the network
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Determine the CPU module firmware versionConnect using GX Works2 or GX Works3 engineering software and navigate to the CPU module diagnostics, or check the device's web interface if enabled, to retrieve the firmware versionAffected if The installed firmware version falls within the vulnerable version range (compare your version to vendor advisories)
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Verify Ethernet communication is enabledCheck the PLC configuration via GX Works2/3 under the Ethernet port settings or CPU module parameters to confirm Ethernet communication is configured and enabledAffected if Ethernet communication is enabled, as the vulnerability is exploitable via network packets
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Check network exposure of the PLCReview firewall rules, network segmentation, and access control lists to determine if the PLC is directly accessible from untrusted networks or the internetAffected if The PLC is reachable from untrusted network segments without proper network filtering
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Inspect for anomalous network trafficMonitor network traffic on ports used by MELSEC protocol (such as port 5007) for unusual packet patterns or high volumes of malformed packets using network monitoring toolsAffected if Unusual or malformed packets targeting the PLC are detected
The environment is affected if MELSEC-Q or MELSEC-L Series PLCs are present with vulnerable firmware versions and are network-accessible, particularly via Ethernet communication.
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 dataApply vendor-supplied firmware updates when available; until then, isolate affected PLCs behind network segmentation, implement strict access controls, and monitor for anomalous packet patterns.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-0803 — 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-2024-0803 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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