CVE-2021-34567
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 · uneditedIn WAGO I/O-Check Service in multiple products an unauthenticated remote attacker can send a specially crafted packet containing OS commands to provoke a denial of service and an limited 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 confidenceWAGO I/O-Check Service contains a vulnerability allowing unauthenticated remote attackers to send specially crafted packets containing OS commands, causing denial of service and a limited out-of-bounds read. The high CVSS score reflects the unauthenticated remote attack vector and OS command execution capability.
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< 18= 18< 18= 18< 18= 18< 18= 18< 18= 18< 18= 18< 18= 18< 18= 18CVSS 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
- Low
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 the WAGO device modelLocate the device label or access the device web interface or management console to determine the exact model number (e.g., 750-8100, 750-8101, 750-8202)Affected if The model is one of the listed affected variants (750 8100, 750 8101, 750 8101/025 000, 750 8102, 750 8102/025 000, 750 8202, 750 8202/000 011, 750 8202/000 012)
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Check the installed firmware versionAccess the device management interface, use the WAGO software tools, or consult device documentation to retrieve the current firmware versionAffected if The firmware version is 18 or any version lower than 18 (the affected range is < 18 or = 18)
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Verify if I/O-Check Service is enabledCheck the device configuration or running services to determine if the I/O-Check Service is active; consult device documentation for the specific configuration location or commandAffected if The I/O-Check Service is running or enabled on the device (this is the vulnerable component that must be present for exploitation)
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Assess network exposure of the I/O-Check ServiceReview network firewall rules, access control lists, or device network configuration to determine if the I/O-Check Service port is accessible from untrusted network segmentsAffected if The I/O-Check Service is reachable from network segments outside the trusted operational technology network (unauthenticated remote vector)
You are affected if your WAGO device model matches one of the affected variants AND the firmware version is 18 or lower AND the I/O-Check Service is enabled and accessible.
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 data18
Restrict network access to the I/O-Check Service via firewall or network segmentation; apply vendor patches when available; disable the service if not required.
- Consultation2.0 h
- Implementation6.0 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 $3,904.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-34567 — 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-2021-34567 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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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