CVE-2021-20999
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 Weidmüller u-controls and IoT-Gateways in versions up to 1.12.1 a network port intended only for device-internal usage is accidentally accessible via external network interfaces. By exploiting this vulnerability the device may be manipulated or the operation may be stopped.
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 confidenceWeidmüller u-controls and IoT-Gateways versions up to 1.12.1 expose a network port intended only for internal device communication through external network interfaces. This critical network misconfiguration allows unauthenticated remote attackers to access internal services, potentially enabling device manipulation or denial of service.
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>= 1.3.0, < 1.9.1>= 1.10.0, < 1.10.3= 1.11.0= 1.12.1>= 1.3.0, < 1.9.1>= 1.10.0, < 1.10.3= 1.11.0= 1.12.1>= 1.3.0, < 1.9.1>= 1.10.0, < 1.10.3= 1.11.0= 1.12.1>= 1.3.0, < 1.9.1>= 1.10.0, < 1.10.3= 1.11.0= 1.12.1CVSS 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.
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Identify the device modelAccess the device management interface or check the device label to confirm the exact model (Uc20 Wl2000 Ac, Uc20 Wl2000 Iot, Iot Gw30, or Iot Gw30 4g Eu).Affected if The device model matches one of the affected products listed in the CVE.
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Determine the installed firmware versionLog into the device web interface, CLI, or management console and navigate to the firmware/version information section. Compare the installed version against the affected ranges: >= 1.3.0 and < 1.9.1; >= 1.10.0 and < 1.10.3; = 1.11.0; = 1.12.1.Affected if The firmware version falls within any of the affected version ranges.
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Identify the exposed internal portReview the CVE advisory or vendor documentation to identify which specific internal service port is being exposed. This is typically a port intended only for internal device communication.Affected if A specific internal port (such as a management or diagnostic port) is identified as exposed.
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Check external network accessibility of the internal portFrom an external network location (outside the expected internal network), attempt to connect to the identified internal port using tools like telnet, netcat, or a port scanner targeting the device's external IP address.Affected if The internal port is reachable from external networks, indicating it is exposed through external interfaces.
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Review firewall and network segmentation configurationExamine the device firewall rules, network configuration, or VLAN settings to determine if the internal port is permitted for external access when it should be restricted to internal communication only.Affected if Firewall rules allow external access to the internal port, or no rule explicitly blocks it.
The device is affected if it is one of the listed models, runs a firmware version within the affected ranges, and has the internal port accessible from external network interfaces.
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 data1.9.11.10.3
Restrict access to the exposed internal port via firewall rules or network segmentation to prevent external access, and apply vendor firmware updates when available.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20999 — 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-2021-20999 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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