CVE-2021-32986
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 · uneditedAfter Automation Direct CLICK PLC CPU Modules: C0-1x CPUs with firmware prior to v3.00 is unlocked by an authorized user, the unlocked state does not timeout. If the programming software is interrupted, the PLC remains unlocked. All subsequent programming connections are allowed without authorization. The PLC is only relocked by a power cycle, or when the programming software disconnects correctly.
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 confidenceIn Automation Direct CLICK PLC C0-1x CPUs prior to v3.00, when an authorized user unlocks the PLC via programming software and the session is interrupted (e.g., connection loss, crash), the PLC remains in an unlocked state indefinitely. This allows any subsequent connection to the PLC without authentication, enabling full program modification, configuration changes, or potential malicious code injection.
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< 3.00< 3.00< 3.00< 3.00< 3.00< 3.00< 3.00< 3.00CVSS 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 PLC model numberConnect to the PLC using the CLICK programming software and check the CPU model information, or query the PLC via its network interface to retrieve the model identifier (e.g., C0 10dd1e D, C0 11dd2e D, etc.)Affected if The model number matches any of the affected variants: C0 10dd1e D, C0 10dd2e D, C0 10dre D, C0 10are D, C0 11dd1e D, C0 11dd2e D, C0 11dre D, or C0 11are D
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Check the firmware versionUsing the CLICK programming software, navigate to the PLC information or system status screen to display the current firmware version. Alternatively, query the PLC via its communication protocol to retrieve the firmware revision.Affected if The firmware version is below 3.00 (e.g., 2.xx, 1.xx)
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Verify if an interrupted session left the PLC unlockedAfter any known connection interruption (network loss, software crash, unexpected disconnect), attempt to connect to the PLC without providing credentials. If the connection succeeds without authentication, the PLC may be in a persistent unlocked state.Affected if The PLC accepts a connection without requiring authentication after a prior session was interrupted
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Confirm the vulnerability conditionCross-reference: if the PLC model is an affected variant AND the firmware version is below 3.00, the device is vulnerable to remaining in an unlocked state after interrupted programming sessions.Affected if Both conditions are true: (1) model is one of the affected C0-1x variants and (2) firmware version is less than 3.00
A user is affected if their CLICK PLC is one of the C0-1x CPU models listed and runs firmware version prior to 3.00, allowing unauthenticated access after session interruption.
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 · scoped3.00
Upgrade CLICK PLC firmware to v3.00 or later. As a compensating control, ensure PLCs are power-cycled after any interrupted programming session, and implement network segmentation to limit exposure of programming ports to authorized engineering workstations only.
Firmware v3.00
- Identify the exact CLICK PLC model number (C0-1x series, e.g., C0-1DD1D, C0-1DD2D, C0-1DR, etc.) from the physical unit or programming software
- Connect to the PLC using CLICK programming software (Automation Direct)
- Navigate to the CPU module information or system settings to check the current firmware version
- If firmware version is less than 3.00, download the firmware update package from the official Automation Direct website (www.automationdirect.com) or contact Automation Direct technical support
- Follow Automation Direct's documented firmware upgrade procedure, which typically involves: a) Backing up the current PLC program, b) Using the programming software to flash the new firmware, c) Verifying the upgrade completed successfully
- After upgrading, verify the firmware now shows version 3.00 or later
- Test that the unlock timeout functions correctly by interrupting a programming session and confirming the PLC relocks automatically
- Re-download the program to the PLC if needed after the firmware update
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation12.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-32986 — 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-2021-32986 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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