CVE-2021-20597
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 · uneditedInsufficiently Protected Credentials vulnerability in Mitsubishi Electric MELSEC iQ-R series Safety CPU modules R08/16/32/120SFCPU firmware versions "26" and prior and Mitsubishi Electric MELSEC iQ-R series SIL2 Process CPU modules R08/16/32/120PSFCPU firmware versions "11" and prior allows a remote unauthenticated attacker to login to the target unauthorizedly by sniffing network traffic and obtaining credentials when registering user information in the target or changing a password.
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 confidenceThis is an Insufficiently Protected Credentials vulnerability in Mitsubishi Electric MELSEC iQ-R series Safety CPU and SIL2 Process CPU modules. The vulnerability allows a remote unauthenticated attacker to obtain credentials by sniffing network traffic during user registration or password change operations. The credentials are transmitted without adequate protection, enabling unauthorized login.
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 versionsall 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 affected MELSEC iQ-R CPU modelsInventory your industrial control system for Mitsubishi Electric Safety CPU or SIL2 Process CPU modules. Look for model numbers R08SFCPU, R16SFCPU, R32SFCPU, R120SFCPU, R08PSFCPU, R16PSFCPU, R32PSFCPU, or R120PSFCPU in your asset inventory or physically on the device.Affected if Any of these eight model numbers are present in the environment
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Check Safety CPU firmware versionAccess the CPU module via GX Works3 engineering software or the device's web interface. Navigate to the CPU module diagnostics and retrieve the firmware version for R08SFCPU, R16SFCPU, R32SFCPU, or R120SFCPU.Affected if The firmware version is below 27, or the version cannot be determined (all versions are affected)
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Check SIL2 Process CPU firmware versionAccess the PSFCPU module via GX Works3 engineering software or the device's web interface. Navigate to the CPU module diagnostics and retrieve the firmware version for R08PSFCPU, R16PSFCPU, R32PSFCPU, or R120PSFCPU.Affected if The firmware version is below 12, or the version cannot be determined (all versions are affected)
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Assess network exposure during credential operationsDetermine whether user registration or password change operations are performed over the network. Review network architecture to check if traffic between the engineering workstation and the affected CPU module passes through shared or untrusted network segments where sniffing could occur.Affected if The CPU module is network-accessible and user credential operations traverse network segments where an attacker could intercept traffic
You are affected if you have any R08/16/32/120SFCPU or R08/16/32/120PSFCPU modules with firmware versions below 27 (for SFCPU) or below 12 (for PSFCPU), and the device is accessible on a network where traffic sniffing is possible during user registration or password changes.
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 dataUpgrade firmware to version 27 or later for R08/16/32/120SFCPU and version 12 or later for R08/16/32/120PSFCPU. Additionally, implement network segmentation and monitor for credential-sniffing attacks until the update is applied.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20597 — 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-2021-20597 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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