CVE-2019-13555
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 Mitsubishi Electric MELSEC-Q Series Q03/04/06/13/26UDVCPU: serial number 21081 and prior, Q04/06/13/26UDPVCPU: serial number 21081 and prior, and Q03UDECPU, Q04/06/10/13/20/26/50/100UDEHCPU: serial number 21081 and prior, MELSEC-L Series L02/06/26CPU, L26CPU-BT: serial number 21101 and prior, L02/06/26CPU-P, L26CPU-PBT: serial number 21101 and prior, and L02/06/26CPU-CM, L26CPU-BT-CM: serial number 21101 and prior, a remote attacker can cause the FTP service to enter a denial-of-service condition dependent on the timing at which a remote attacker connects to the FTP server on the above CPU modules.
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 remote attacker can cause the FTP service on affected Mitsubishi Electric MELSEC-Q Series (Q03/04/06/13/26UDVCPU, Q04/06/13/26UDPVCPU, Q03UDECPU, Q04/06/10/13/20/26/50/100UDEHCPU) and MELSEC-L Series (L02/06/26CPU, L26CPU-BT, L02/06/26CPU-P, L26CPU-PBT, L02/06/26CPU-CM, L26CPU-BT-CM) CPU modules to enter a denial-of-service condition by connecting to the FTP server at a specific timing dependent on the attacker's connection.
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<= 21081<= 21081<= 21081<= 21081<= 21101<= 21101<= 21101<= 21101CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/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 the MELSEC CPU modelLocate the model number printed on the CPU module or check the device configuration. Confirm it is one of the Q Series models (Q03/04/06/13/26UDVCPU, Q04/06/13/26UDPVCPU, Q03UDECPU, Q04/06/10/13/20/26/50/100UDEHCPU) or L Series models (L02/06/26CPU, L26CPU-BT, L02/06/26CPU-P, L26CPU-PBT, L02/06/26CPU-CM, L26CPU-BT-CM).Affected if The model is one of the listed affected products.
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Check the firmware versionAccess the CPU module via engineering software (such as GX Works2 or GX Works3) or the device web interface to view the firmware version. Compare it against the affected version ranges: Q Series <= 21081, L Series <= 21101.Affected if The firmware version is at or below 21081 for Q Series, or at or below 21101 for L Series.
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Confirm FTP service is enabledCheck the CPU module configuration settings via the engineering software or device web interface to determine if the FTP server function is enabled and running.Affected if The FTP server function is enabled on the device.
The environment is affected if the device is a vulnerable MELSEC-Q or L Series CPU module with FTP enabled and firmware version at or below the threshold (21081 for Q Series, 21101 for L Series).
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 network segmentation and firewall rules to restrict access to the FTP service. Upgrade firmware to versions beyond serial number 21082 for Q Series or 21102 for L Series to resolve the timing-based DoS vulnerability.
- Consultation4.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-13555 — 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-2019-13555 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
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