CVE-2018-7790
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 Management Error 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 replay authentication sequences. If an attacker exploits this vulnerability and connects to a Modicon M221, the attacker can upload the original program from the PLC.
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 contains an information management error vulnerability in its authentication mechanism that allows replay attacks. An attacker can capture and replay valid authentication sequences to bypass authentication and gain unauthorized access to the PLC, enabling program extraction.
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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 modelLocate the PLC nameplate or check the device properties in the engineering software (SoMachine or EcoStruxure Machine Expert) to confirm the model is Modicon M221Affected if The device is NOT a Modicon M221 PLC, then this CVE does not apply
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Determine the firmware versionAccess the PLC via the engineering software and check the firmware version in the device properties, or access the web server if enabled and look at the firmware information pageAffected if The firmware version is 1.6.2.0 or higher (these versions are NOT affected); versions below 1.6.2.0 ARE affected
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Verify if remote management interfaces are enabledCheck the PLC configuration for enabled communication services such as the built-in web server, Modbus TCP, or other remote access methods that could accept authentication attemptsAffected if Remote management interfaces are disabled and the PLC is physically isolated, the exploit path is significantly reduced but the underlying vulnerable code may still exist in the firmware
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Check network accessibilityVerify if the PLC is directly accessible from any network by reviewing network configuration, firewall rules, and VLAN assignmentsAffected if The PLC is exposed on untrusted networks, an attacker could potentially capture and replay authentication packets
The environment is affected if the device is a Schneider Electric Modicon M221 PLC running firmware versions prior to 1.6.2.0 and has remote management interfaces enabled or network accessibility.
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.
dbcve · scoped1.6.2.0
Update Modicon M221 firmware to V1.6.2.0 or later to address the replay attack vulnerability. Additionally, implement network segmentation and monitor for suspicious authentication patterns as compensating controls.
Modicon M221 Firmware V1.6.2.0 or later
- 1. Identify the current firmware version of the Modicon M221 PLC by accessing it via Schneider Electric's programming software (SoMachine or EcoStruxure Machine Expert).
- 2. Navigate to Schneider Electric's official support website and download firmware version 1.6.2.0 or later for the Modicon M221.
- 3. Follow Schneider Electric's official firmware update procedure: connect to the PLC, enter boot mode if required, and upload the new firmware file using the programming software.
- 4. After upgrading, verify the firmware version has been successfully updated to 1.6.2.0 or later.
- 5. Test that the PLC operates normally and that authentication functions properly after the upgrade.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-7790 — 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-2018-7790 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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