CVE-2021-30194
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 V2 Web-Server before 1.1.9.20 has an Out-of-bounds Read.
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 V2 Web-Server before version 1.1.9.20 contains an out-of-bounds read vulnerability. This memory safety flaw allows a remote attacker to read memory contents beyond allocated buffer boundaries, potentially exposing sensitive information or causing unpredictable behavior. The critical severity (9.1) suggests the vulnerability is remotely exploitable without authentication.
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< fw08< fw08< fw08< fw15< fw15< fw15< fw15< fw16CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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.
-
Identify the Wago 750 controller modelLocate the model number on the physical device label or check the device documentation/inventory. Look for model numbers: 750-880, 750-881, 750-882, 750-885, 750-889, 750-890, 750-891, or 750-893.Affected if The device is one of these eight Wago 750 controller models.
-
Determine the installed firmware versionAccess the controller via its web interface, PLC programming software (e.g., CODESYS), or management console and retrieve the firmware version information. This is typically found in system info, device properties, or firmware update sections.Affected if The firmware version cannot be determined or the retrieved version is below the threshold for your model.
-
Compare firmware version against affected rangesMatch your firmware version to the affected range: for models 880 check < fw16, for models 881/882/885/889 check < fw15, for models 890/891/893 check < fw08.Affected if Your installed firmware version falls below the specified threshold for your model number.
-
Confirm the CODESYS V2 Web-Server is accessibleAttempt to access the web server interface by navigating to the controller's IP address on port 80 or 443, or check if the web server service is listed as running in the controller's service status.Affected if The web server interface is accessible and responds to HTTP/HTTPS requests.
If you have a Wago 750 series controller (880, 881, 882, 885, 889, 890, 891, or 893) with firmware below the threshold (fw08/fw15/fw16 depending on model) AND the CODESYS V2 Web-Server is accessible on the network, your environment is affected by CVE-2021-30194.
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 CODESYS V2 Web-Server to version 1.1.9.20 or later. As a compensating control, restrict network access to the web server interface using firewalls or network segmentation to limit exposure to untrusted networks.
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 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 $3,680.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30194 — 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-2021-30194 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