CVE-2021-33485
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 Control Runtime system before 3.5.17.10 has a Heap-based Buffer Overflow.
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 confidenceA heap-based buffer overflow vulnerability exists in the CODESYS Control Runtime system versions prior to 3.5.17.10. This memory corruption flaw could allow remote attackers to execute arbitrary code or cause a denial of service by overflowing a heap-allocated buffer.
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< 4.2.0.0<= 4.2.0.0< 3.5.17.10< 3.5.17.10< 3.5.17.10< 3.5.17.10< 3.5.17.10< 3.5.17.10CVSS 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.
-
Identify installed CODESYS productCheck the installed program files for CODESYS Control components. Common installation paths: C:\Program Files\CODESYS or C:\Program Files (x86)\CODESYS. Look for directories like 'CODESYS Control', 'CODESYS Control Rte', 'CODESYS Hmi', or check Add/Remove Programs for CODESYS entries.Affected if Any CODESYS Control, Control Rte, Runtime System Toolkit, Win Sl, Embedded Target Visu Toolkit, Hmi, or Remote Target Visu Toolkit product is installed
-
Determine installed version via registryCheck Windows Registry under HKLM\SOFTWARE\CODESYS for the installed version, or check the specific product's registry key under HKLM\SOFTWARE\CODESYS\CODESYS Control Runtime or similar paths. The version may also be displayed in the CODESYS Development System under 'Help > About'.Affected if Version cannot be determined or is below the safe thresholds
-
Compare version against affected rangesIf using Codesys Control version 4.x, check if version is less than 4.2.0.0. For Codesys Control Rte, Runtime System Toolkit, Win Sl, Embedded Target Visu Toolkit, Hmi, or Remote Target Visu Toolkit, check if version is less than 3.5.17.10.Affected if Installed version falls within: Codesys Control < 4.2.0.0 (or <= 4.2.0.0), or any of the 3.5.x series products < 3.5.17.10
-
Verify runtime component is activeConfirm the CODESYS Control Runtime service is running on the system. In Windows, open Services and look for 'CODESYS Control' or check if the runtime process (CODESYSControlService.exe) is active.Affected if The runtime service is installed and running, making the vulnerability exploitable
If any CODESYS Control product (Rte, Runtime System Toolkit, Win Sl, Embedded Target Visu, Hmi, Remote Target Visu) with version below 3.5.17.10, or Codesys Control below 4.2.0.0 is installed and the runtime is active, the environment is affected by CVE-2021-33485.
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 · scoped3.5.17.104.2.0.0
Upgrade CODESYS Control Runtime to version 3.5.17.10 or later to address the vulnerability. Given the critical CVSS score, prioritize this update in the deployment schedule.
CODESYS Control Runtime version 3.5.17.10 or later (for most products); Control product version 4.2.0.0 or later
- 1. Identify all deployed CODESYS Control Runtime installations and their current versions
- 2. For 'Control' product: Upgrade to version 4.2.0.0 or later
- 3. For all other affected products (Control Rte, Control Runtime System Toolkit, Control Win Sl, Embedded Target Visu Toolkit, Hmi, Remote Target Visu Toolkit): Upgrade to version 3.5.17.10 or later
- 4. Verify the upgrade was successful by checking the runtime version after patching
- 5. Test the control application functionality to ensure the upgrade does not affect runtime behavior
- 6. Update change management and inventory systems to reflect the patched versions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,288.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-33485 — 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-2021-33485 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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