CVE-2018-7789
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 Improper Check for Unusual or Exceptional Conditions vulnerability exists in Schneider Electric's Modicon M221 product (all references, all versions prior to firmware V1.6.2.0). The vulnerability allows unauthorized users to remotely reboot Modicon M221 using crafted programing protocol frames.
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 Modicon M221 PLC has an improper check for unusual or exceptional conditions in its programming protocol implementation. This allows unauthenticated remote attackers to send crafted protocol frames that trigger an unexpected reboot of the device.
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< 1.6.2.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the device modelCheck the PLC hardware label or use Schneider Electric engineering software (SoMachine Basic or EcoStruxure Machine Expert) to query the device identity. Look for 'Modicon M221' or 'M221' marking on the physical unit or in the device properties.Affected if The device is NOT a Modicon M221 PLC (different models are not affected by this CVE).
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Determine the firmware versionUsing Schneider Electric's programming software (SoMachine Basic or EcoStruxure Machine Expert), connect to the PLC and access the device properties or system information. The firmware version is typically displayed in the 'Controller Properties' or 'System Info' section. Alternatively, check the firmware version label on the device if physically accessible.Affected if The installed firmware version is anything less than 1.6.2.0 (e.g., 1.5.x, 1.4.x, etc.).
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Assess network exposure of programming protocolReview network firewall rules and access control lists (ACLs) to determine if the PLC's programming protocol ports (typically TCP/502 for Modbus and vendor-specific ports for the SoMachine protocol) are accessible from untrusted or external networks. Use network scanning tools to confirm which ports are listening on the PLC's IP address.Affected if The programming protocol ports are accessible from untrusted networks or the internet without authentication barriers.
You are affected if you have a Modicon M221 PLC running firmware version below 1.6.2.0 with exposed programming protocol access from untrusted networks.
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 data1.6.2.0
Upgrade Modicon M221 firmware to V1.6.2.0 or later. Additionally, implement network segmentation and firewall rules to restrict unauthorized access to the PLC's programming protocol ports.
- Consultation3.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-7789 — 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-2018-7789 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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