CVE-2021-29241
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 · uneditedCODESYS Gateway 3 before 3.5.16.70 has a NULL pointer dereference that may result in a denial of service (DoS).
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 confidenceCODESYS Gateway 3 versions before 3.5.16.70 contain a NULL pointer dereference vulnerability that can be triggered to cause a denial of service condition. The vulnerability has a CVSS score of 7.5 (HIGH), indicating significant availability impact.
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>= 3.0, < 4.0.1.0>= 3.0, < 4.0.1.0>= 3.0, < 4.0.1.0>= 3.0, < 4.0.1.0>= 3.0, < 3.5.16.0>= 3.0, < 3.5.16.0>= 3.0, < 4.0.1.0>= 3.0, < 3.5.16.70CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 installed CODESYS productsCheck system for installed CODESYS Control packages. On Windows, look in C:\Program Files\CODESYS or check registry under HKEY_LOCAL_MACHINE\SOFTWARE\CODESYS. On Linux, check /opt/codesys or using package manager (dpkg -l | grep codesys or rpm -qa | grep codesys)Affected if Any CODESYS Control product (Beaglebone, Empc, IoT2000, Linux, PFC100, PFC200, Raspberry Pi) or Runtime System Toolkit is installed
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Determine CODESYS Gateway 3 versionLocate the Gateway3.exe or CmpGateway application file. Right-click > Properties > Details tab to view File Version. Alternatively, open CODESYS Development System, go to Tools > Options > Update Manager to see installed components and versionsAffected if Version is below 3.5.16.70 for Runtime System Toolkit, or below 3.5.16.0 for PFC100/PFC200, or below 4.0.1.0 for Beaglebone/Empc/IoT2000/Linux/Raspberry Pi variants
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Check if Gateway service is activeOn Windows, open Services.msc and look for 'CODESYS Gateway' service. On Linux, run systemctl status codesysgateway or ps aux | grep gateway. Check if the service is in running stateAffected if CODESYS Gateway 3 service is running and version is in the affected range
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Verify CODESYS Control runtime versionIf using a hardware device (Beaglebone, Raspberry Pi, PFC100/200, IoT2000), connect to the device via SSH or console. Check runtime version by looking at the installed package: on Raspberry Pi check /opt/codesys/CODESYSControl.cfg or run codesysinfo command if availableAffected if Runtime version installed on the device is prior to 4.0.1.0 (for most SL variants) or prior to 3.5.16.0 (for PFC100/PFC200)
The environment is affected if any CODESYS Control product or Runtime System Toolkit is installed with a version lower than the fixed releases (3.5.16.70, 3.5.16.0, or 4.0.1.0 depending on product) and the Gateway component is active.
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 data3.5.16.03.5.16.704.0.1.0
Upgrade CODESYS Gateway 3 to version 3.5.16.70 or later to resolve the NULL pointer dereference. Apply the vendor patch following standard change management procedures.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29241 — 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-2021-29241 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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