CVE-2019-6851
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 · uneditedA CWE-538: File and Directory Information Exposure vulnerability exists in Modicon M580, Modicon M340, Modicon Premium , Modicon Quantum (all firmware versions), which could cause the disclosure of information from the controller when using TFTP protocol.
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 · high confidenceA CWE-538 File and Directory Information Exposure vulnerability exists in Schneider Electric Modicon PLCs (M580, M340, Premium, Quantum) where the TFTP protocol implementation allows unauthorized disclosure of controller information, configuration files, or system details to remote attackers.
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 versionsall versionsall versionsall versionsall versionsall 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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 PLC modelDetermine if the target device is a Schneider Electric Modicon M580, M340, Premium, or Quantum controller, or uses Tsxmcpc002m, Tsxmcpc512k, Tsxmfpp001m, Tsxmfpp002m, Tsxmfpp004m, or Tsxmfpp512k firmware modules. Check the device label, Unity Pro/EcoStruxure programming software project, or SNMP/system information.Affected if The device is any of these models and the TFTP service is active.
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Verify TFTP service statusOn the PLC, navigate to the network configuration settings (via Unity Pro, EcoStruxure, or the device web interface if available) and check whether the TFTP server/service is enabled. Alternatively, check if UDP port 69 is listening on the controller.Affected if TFTP is enabled and UDP port 69 is open on the controller.
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Check TFTP network exposurePerform a UDP port scan against the device on port 69 from an external or untrusted network segment to determine if the TFTP service is reachable. Review firewall rules and network segmentation configurations around the PLC.Affected if TFTP port 69 is accessible from untrusted or external network segments.
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Assess TFTP access controlsReview the PLC network configuration to determine if TFTP access is restricted to specific trusted IP addresses, or if any unauthenticated requests are permitted to read files.Affected if TFTP accepts requests from any source without IP-based restrictions or authentication.
The environment is affected if the PLC is a Modicon M580, M340, Premium, or Quantum (or uses the listed Tsxmcpc/Tsxmfpp firmware modules), the TFTP service is enabled, and the TFTP port is accessible from untrusted networks without IP restrictions.
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 dataDisable the TFTP service on affected controllers if not required for operations, or restrict TFTP traffic through network segmentation and firewall rules to trusted sources only.
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2019-6851 — 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-2019-6851 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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