CVE-2018-7851
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 · uneditedCWE-119: Buffer errors vulnerability exists in Modicon M580 with firmware prior to V2.50, Modicon M340 with firmware prior to V3.01, BMxCRA312xx with firmware prior to V2.40, All firmware versions of Modicon Premium and 140CRA312xxx when sending a specially crafted Modbus packet, which could cause a denial of service to the device that would force a restart to restore availability.
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-119 buffer errors vulnerability in Schneider Electric Modicon controllers (M580, M340, BMxCRA312xx, Premium, 140CRA312xxx) allows remote attackers to cause denial of service by sending specially crafted Modbus packets, triggering a buffer overflow that forces the device to restart.
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< 2.50< 3.01< 2.40all 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 Modicon controller modelAccess the controller via Schneider Electric programming software (Unity Pro, EcoStruxure, or via the device's web interface/HMI) and record the exact model number: M580, M340, BMxCRA312xx, Modicon Premium, or 140cra312xxx.Affected if The device is any of these five model families (M580, M340, BMxCRA, Premium, or 140cra312xxx).
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Determine the installed firmware versionCheck the firmware version through the controller's web interface, HMI, or via the programming software (Unity Pro/EcoStruxure) under the controller properties or device information section.Affected if Firmware version is below: M580 < 2.50, M340 < 3.01, BMxCRA312xx < 2.40, or any version for Premium/140cra312xxx.
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Verify Modbus communication is enabledCheck the controller configuration for Modbus TCP or Modbus serial communication settings. In the programming software, review the communication modules and protocol configuration to confirm Modbus is active.Affected if Modbus protocol (TCP or serial) is enabled and the controller is network-accessible. This is the attack vector required for exploitation.
If the device is a Schneider Electric Modicon controller (M580, M340, BMxCRA, Premium, or 140cra312xxx) with firmware below the safe thresholds and has Modbus communication enabled and network-accessible, the environment is affected by CVE-2018-7851.
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 data2.402.503.01
Upgrade firmware to vendor-specified versions (M580: V2.50+, M340: V3.01+, BMxCRA312xx: V2.40+). For Modicon Premium and 140CRA312xxx (all versions affected), contact vendor for compensating controls or firmware availability.
- Consultation6.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2018-7851 — 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-2018-7851 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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- Version or environment caveats, and links to real fixes
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