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750 893 FirmwareOperating system · Wago

CVE-2021-30193

CRITICAL · 9.8 CVSS v3.1 Published 2021-05-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
CODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Write.

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 confidence

CODESYS V2 Web-Server before version 1.1.9.20 contains an out-of-bounds write vulnerability. This memory corruption flaw allows writing data beyond allocated buffer boundaries, which can potentially enable remote code execution or cause denial of service. The critical severity (9.8) indicates network-exploitable, low-complexity attacks with complete impact on confidentiality, integrity, and availability.

MitigationUpgrade CODESYS V2 Web-Server to version 1.1.9.20 or later to remediate the out-of-bounds write vulnerability. If immediate patching is not feasible, restrict network access to the web server interface as a compensating control.

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
750 893 FirmwareOperating system
Affected:< fw08
750 891 FirmwareOperating system
Affected:< fw08
750 890 FirmwareOperating system
Affected:< fw08
750 889 FirmwareOperating system
Affected:< fw15
750 885 FirmwareOperating system
Affected:< fw15
750 882 FirmwareOperating system
Affected:< fw15
750 881 FirmwareOperating system
Affected:< fw15
750 880 FirmwareOperating system
Affected:< fw16

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify CODESYS V2 Web-Server presence
    Check if the CODESYS V2 Web-Server service or process is running on the system. Look for web server processes or check network listeners on common HTTP ports (e.g., port 80, 8080, or vendor-defined ports).
    Affected if The CODESYS V2 Web-Server is installed and running on the target system.
  2. Determine CODESYS V2 Web-Server version
    Access the web server version information through its management interface, check the installed software package version, or query the web server directly via HTTP headers or API endpoints if available.
    Affected if The installed version is earlier than 1.1.9.20.
  3. Identify Wago 750 controller model
    Check the system inventory, device documentation, or query the PLC/controller for its model identifier (e.g., 750-893, 750-891, 750-890, 750-889, 750-885, 750-882, 750-881, or 750-880).
    Affected if The system is a Wago 750 series controller matching one of the affected models.
  4. Check Wago firmware version
    Access the controller's web interface, use Wago's management tools, or query the device firmware version through its PLC programming interface or diagnostics.
    Affected if The firmware version is below the threshold specified for the model (fw08 for 893/891/890, fw15 for 889/885/882/881, or fw16 for 880).

A system is affected if it runs CODESYS V2 Web-Server version below 1.1.9.20, or if it is a Wago 750 series controller with firmware below the specified threshold for that model.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade CODESYS V2 Web-Server to version 1.1.9.20 or later to remediate the out-of-bounds write vulnerability. If immediate patching is not feasible, restrict network access to the web server interface as a compensating control.

Recommended fix High confidence

CODESYS V2 Web-Server version 1.1.9.20 (firmware: fw08 or later for 750 893/891/890; fw15 or later for 750 889/885/882/881; fw16 or later for 750 880)

  1. 1. Identify the specific 750 series device model (750 893, 750 891, 750 890, 750 889, 750 885, 750 882, 750 881, or 750 880) from the affected hardware
  2. 2. Check the current firmware version installed on the device
  3. 3. Navigate to the CODESYS customer portal (customers.codesys.com) and locate the firmware update for your specific device model
  4. 4. Download the appropriate firmware update: fw08 or higher for models 750 893/891/890; fw15 or higher for models 750 889/885/882/881; fw16 or higher for model 750 880
  5. 5. Review the firmware upgrade instructions provided by the vendor
  6. 6. Apply the firmware update following the vendor's recommended procedure, ensuring stable power during the process
  7. 7. After upgrade, verify the CODESYS V2 Web-Server version is 1.1.9.20 or later
  8. 8. Confirm the vulnerability is resolved by reviewing system logs and functionality
Caveat Firmware updates may require system downtime and should be tested in a non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in 750 893 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-30193 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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