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Modicon M340 FirmwareOperating system · Schneider Electric

CVE-2019-6819

HIGH · 7.5 CVSS v3.1 Published 2019-05-22
Fix available
A fix is available. Upgrade to 2.80 / 3.01 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A CWE-754: Improper Check for Unusual or Exceptional Conditions vulnerability exists which could cause a possible Denial of Service when specific Modbus frames are sent to the controller in the products: Modicon M340 - firmware versions prior to V3.01, Modicon M580 - firmware versions prior to V2.80, All firmware versions of Modicon Quantum and Modicon Premium.

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 confidence

A CWE-754 vulnerability in Schneider Electric Modicon PLCs (M340, M580, Quantum, Premium) allows attackers to cause denial of service by sending specially crafted Modbus frames. The controller fails to properly handle unusual or exceptional conditions in these frames, causing it to crash or become unresponsive.

MitigationApply firmware updates: Modicon M340 to V3.01 or later, Modicon M580 to V2.80 or later. For Modicon Quantum and Premium (all versions), contact vendor for patches. Consider network segmentation to limit Modbus exposure to trusted devices.

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
Modicon M340 FirmwareOperating system
Affected:< 3.01
Modicon M580 FirmwareOperating system
Affected:< 2.80
Modicon Quantum FirmwareOperating system
Affected:all versions
Modicon Premium FirmwareOperating system
Affected:all versions

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify PLC model
    Locate the physical PLC hardware or check system documentation to confirm the Modicon model (M340, M580, Quantum, or Premium)
    Affected if The PLC is any of these four models
  2. Check Modicon M340 firmware version
    Access the PLC via Schneider Unity software, EcoStruxure Control Expert, or the PLC web interface and navigate to the firmware version information
    Affected if Firmware version is below 3.01
  3. Check Modicon M580 firmware version
    Access the PLC via Schneider Unity software, EcoStruxure Control Expert, or the PLC web interface and navigate to the firmware version information
    Affected if Firmware version is below 2.80
  4. Confirm Modicon Quantum or Premium firmware version
    Access the PLC via Schneider Unity software, EcoStruxure Control Expert, or the PLC web interface and navigate to the firmware version information
    Affected if Any version of Quantum or Premium firmware is installed (all versions affected)
  5. Verify Modbus communication is enabled
    Check PLC configuration in the programming software to confirm Modbus TCP or Modbus Serial communication is configured and active
    Affected if Modbus communication is enabled and accessible
  6. Assess network exposure of Modbus service
    Review network segmentation and firewall rules to determine if the Modbus port (502 TCP for Modbus TCP) is accessible from untrusted networks
    Affected if Modbus service is reachable from networks outside the trusted control system zone

Your environment is affected if you operate a Modicon M340 with firmware < 3.01, a Modicon M580 with firmware < 2.80, or any version of Modicon Quantum or Premium, and Modbus communication is enabled and accessible to the attacker.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 2.80 / 3.01 or later
Fixed in 2.803.01
Interim mitigation

Apply firmware updates: Modicon M340 to V3.01 or later, Modicon M580 to V2.80 or later. For Modicon Quantum and Premium (all versions), contact vendor for patches. Consider network segmentation to limit Modbus exposure to trusted devices.

Fix this in Modicon M340 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-6819 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data