CVE-2018-7812
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 · uneditedAn Information Exposure through Discrepancy vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 where the web server sends different responses in a way that exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not.
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 confidenceThe embedded web servers in Modicon M340, Premium, Quantum PLCs and BMXNOR0200 expose security-relevant information by sending different HTTP responses depending on whether operations succeed or fail. This information disclosure through response discrepancy allows attackers to infer system state and operation outcomes.
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 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:3.0/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 PLC modelDetermine the exact model of the PLC in your environment. Common methods include checking device labeling, reviewing engineering documentation, or querying the device through its management interface or programming software.Affected if The PLC model is Modicom M340, Modicom Premium, Modicom Quantum, or Modicom Bmxnor0200h
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Confirm web server is enabledAccess the PLC configuration or programming software (such as Unity Pro or EcoStruxure) and check whether the embedded web server feature is enabled in the device settings.Affected if The embedded web server is enabled and running on the PLC
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Check network accessibility of web serverAttempt to reach the PLC IP address on HTTP ports (typically port 80 or 443) from a network location. Use a browser or curl command to confirm the web interface is accessible.Affected if The PLC web interface is reachable over the network from locations outside of isolated management VLANs
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Test for response discrepancySend legitimate HTTP requests to the web server (such as accessing known pages) and then send malformed or invalid requests. Compare the HTTP response codes, headers, and body content between valid and invalid operations.Affected if The web server returns measurably different responses (different status codes, error messages, or timing) depending on whether operations succeed or fail, allowing inference of system state
You are affected if your PLC is a Modicom M340, Premium, Quantum, or BMXNOR0200h with the embedded web server enabled and exposed on the network.
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 dataIsolate affected PLCs on restricted network segments, disable the embedded web server if not operationally required, and apply vendor firmware updates when available from Schneider Electric.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 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 $8,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-7812 — 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-2018-7812 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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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.
- 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