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Ie Wl Bl Ap Cl Eu FirmwareOperating system · Weidmueller

CVE-2021-33539

HIGH · 7.2 CVSS v3.1 Published 2021-06-25
Fix available
A fix is available. Upgrade to after 1.16.18 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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
In Weidmueller Industrial WLAN devices in multiple versions an exploitable authentication bypass vulnerability exists in the hostname processing. A specially configured device hostname can cause the device to interpret selected remote traffic as local traffic, resulting in a bypass of web authentication. An attacker can send authenticated SNMP requests to trigger this vulnerability.

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 confidence

This is an authentication bypass vulnerability in Weidmueller Industrial WLAN devices where specially crafted hostname processing causes the device to misclassify remote traffic as local traffic, bypassing web authentication. The vulnerability is triggered via authenticated SNMP requests.

MitigationApply vendor-supplied firmware updates to address the hostname processing vulnerability. As an interim control, restrict network access to SNMP management interfaces and implement network segmentation to limit exposure to authenticated attackers.

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
Ie Wl Bl Ap Cl Eu FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wlt Bl Ap Cl Eu FirmwareOperating system
Affected:<= 1.16.18<= v1.11.10
Ie Wl Bl Ap Cl Us FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wlt Bl Ap Cl Us FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wl Vl Ap Br Cl Eu FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wlt Vl Ap Br Cl Eu FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wl Vl Ap Br Cl Us FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10
Ie Wlt Vl Ap Br Cl Us FirmwareOperating system
Affected:<= 1.16.18<= 1.11.10

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/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 the Weidmueller device model
    Access the device management interface or check the physical device label to confirm the exact model number (e.g., Ie WL BL AP CL EU, Ie WLT BL AP CL US, etc.) from the affected product list.
    Affected if The device model matches any of the following prefixes: Ie Wl Bl Ap, Ie Wlt Bl Ap, Ie Wl Vl Ap Br, Ie Wlt Vl Ap Br.
  2. Check the installed firmware version
    Log into the device web interface or use SNMP (if accessible) to retrieve the current firmware version. This is typically found under System > Firmware, System > Information, or via SNMP OID for system firmware version.
    Affected if The firmware version is less than or equal to 1.16.18, or between 1.11.11 and 1.11.10 (inclusive), indicating a version <= 1.11.10.
  3. Verify if SNMP is enabled
    Check the device configuration for SNMP settings. In the web interface, look under Services > SNMP or Network > SNMP Management. Confirm whether SNMP community strings are configured and the SNMP service is active.
    Affected if SNMP is enabled and configured with community strings, as the vulnerability requires authenticated SNMP requests to trigger the hostname processing flaw.
  4. Confirm web authentication settings
    Access the wireless security or access control configuration panel. Verify whether web-based authentication is required for client/bridge connections and check for any bypass rules related to local vs. remote traffic classification.
    Affected if Web authentication is configured and the device uses hostname-based traffic classification for local/remote distinction.

Your device is affected if it is a Weidmueller Industrial WLAN device from the affected model list, running firmware version <= 1.16.18 or <= 1.11.10, with SNMP enabled and web authentication configured.

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.

From vendor data
Upgrade available Upgrade to a release after 1.16.18
Interim mitigation

Apply vendor-supplied firmware updates to address the hostname processing vulnerability. As an interim control, restrict network access to SNMP management interfaces and implement network segmentation to limit exposure to authenticated attackers.

Fix this in Ie Wl Bl Ap Cl Eu Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2021-33539 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