CVE-2020-7566
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 · uneditedA CWE-334: Small Space of Random Values vulnerability exists in Modicon M221 (all references, all versions) that could allow the attacker to break the encryption keys when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller.
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 confidenceThe Modicon M221 PLC implements encryption with insufficient entropy in its random value generation (CWE-334). An attacker who captures network traffic between EcoStruxure Machine-Basic software and the M221 controller can exploit the small keyspace to recover encryption keys through cryptanalysis, compromising the confidentiality of communications.
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 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 the PLC modelLocate the physical PLC hardware or check the device inventory/asset management system to confirm the model number is Modicon M221Affected if The device is confirmed to be a Schneider Electric Modicon M221 PLC
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Determine firmware versionAccess the PLC through EcoStruxure Machine-Basic software or the programming tool and check the firmware version displayed in the device properties or system informationAffected if Any firmware version is present (all versions are affected)
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Verify network exposureReview network architecture documentation or use network scanning to determine if the PLC is accessible from network segments outside the trusted control system networkAffected if The PLC has an IP address on a network accessible to untrusted users or systems
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Confirm encryption-enabled communicationCheck if EcoStruxure Machine-Basic software is used to communicate with the M221 controller over the networkAffected if EcoStruxure Machine-Basic software communicates with the M221 over the network using encryption that relies on the weak random number generation
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Assess traffic interception riskEvaluate whether an attacker could capture network packets between EcoStruxure Machine-Basic and the M221 controller (check for switch ports, network taps, or vulnerabilities allowing traffic capture)Affected if Network traffic between the engineering workstation and PLC could be captured by an attacker on the network
If the environment contains a Modicon M221 PLC with network connectivity to EcoStruxure Machine-Basic software, the cryptographic flaw affects all firmware versions and the key can be recovered from captured traffic.
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 dataImplement network segmentation to isolate the PLC from untrusted networks and prevent man-in-the-middle traffic capture; contact Schneider Electric for firmware updates addressing the cryptographic design flaw.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-7566 — 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-2020-7566 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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