How severe is CVE-2021-33539?

CVE-2021-33539 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-33539 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33539?

CVE-2021-33539 primarily affects Weidmueller Ie-wl-bl-ap-cl-eu Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33539?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33539 published?

CVE-2021-33539 was published on 2021-06-25 and last updated on 2026-06-17.

CVE-2021-33539

CVE-2021-33539 is a high-severity vulnerability in Weidmueller Ie-wl-bl-ap-cl-eu Firmware with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v2: 6.5
EPSS exploit prediction: 1% (60th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Weidmueller Ie-wl-bl-ap-cl-eu Firmware
Published: 2021-06-25
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-33539?: 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.
How severe is CVE-2021-33539?: CVE-2021-33539 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-33539 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33539?: CVE-2021-33539 primarily affects Weidmueller Ie-wl-bl-ap-cl-eu Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33539?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33539 published?: CVE-2021-33539 was published on 2021-06-25 and last updated on 2026-06-17.

References

https://cert.vde.com/en-us/advisories/vde-2021-026

Affected products (8)

cpe:2.3:o:weidmueller:ie-wl-bl-ap-cl-eu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wlt-bl-ap-cl-eu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wl-bl-ap-cl-us_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wlt-bl-ap-cl-us_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wl-vl-ap-br-cl-eu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wlt-vl-ap-br-cl-eu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wl-vl-ap-br-cl-us_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:weidmueller:ie-wlt-vl-ap-br-cl-us_firmware:*:*:*:*:*:*:*:*

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Other CWE-287 (Improper Authentication) vulnerabilities

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CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →