CVE-2021-37400
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 attacker may obtain the user credentials from the communication between the PLC and the software. As a result, the PLC user program may be uploaded, altered, and/or downloaded.
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 confidenceThis is an authentication/credential exposure vulnerability in industrial control systems where an attacker can intercept user credentials from the unencrypted or inadequately protected communication between a PLC and its associated software. With stolen credentials, attackers can upload, modify, or download PLC user programs, achieving full control of the industrial process.
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<= 2.12.1<= 1.3.1<= 8.19.1<= 2.31<= 1.91<= 2.31<= 2.32<= 2.31CVSS 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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Check Idec Data File Manager versionOpen the application and navigate to Help > About, or check the installed software listing in Windows Programs and FeaturesAffected if The installed version is 2.12.1 or earlier
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Check Idec Windedit versionOpen the application and navigate to Help > About, or check the installed software listing in Windows Programs and FeaturesAffected if The installed version is 1.3.1 or earlier
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Check Idec Windldr versionOpen the application and navigate to Help > About, or check the installed software listing in Windows Programs and FeaturesAffected if The installed version is 8.19.1 or earlier
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Check Idec Microsmart PLC firmware versionConnect to the PLC using the programming software and access the firmware version information in the PLC diagnostics or system information screenAffected if The firmware version is 2.31 or earlier for Fc6b, 2.32 or earlier for Fc6a, or 1.91 or earlier for Fc6a (Plus variant)
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Check Idec Ft1a Smartaxix Pro firmware versionConnect to the PLC using the programming software and access the firmware version information in the PLC diagnostics or system information screenAffected if The firmware version is 2.31 or earlier
You are affected if any Idec software or firmware version matches or is below the affected versions listed, and communication between the PLC and software is unencrypted.
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 TLS encryption or VPN tunneling for all PLC-to-software communications, enforce certificate-based authentication, and rotate credentials regularly to prevent unauthorized access.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 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 $8,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37400 — 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-2021-37400 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