How severe is CVE-2021-34578?

CVE-2021-34578 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-34578 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-2021-34578?

CVE-2021-34578 primarily affects Wago 750-890/040-000 Firmware. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34578?

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

When was CVE-2021-34578 published?

CVE-2021-34578 was published on 2021-08-31 and last updated on 2026-06-17.

CVE-2021-34578

CVE-2021-34578 is a critical-severity vulnerability in Wago 750-890/040-000 Firmware with a CVSS 3.x base score of 9.8. 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: Critical (CVSS 3.x base score 9.8)
CVSS v2: 6.8
EPSS exploit prediction: 1% (60th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Wago 750-890/040-000 Firmware
Published: 2021-08-31
Last modified: 2026-06-17

Description

This vulnerability allows an attacker who has access to the WBM to read and write settings-parameters of the device by sending specifically constructed requests without authentication on multiple WAGO PLCs in firmware versions up to FW07.

Frequently asked questions

What is CVE-2021-34578?: This vulnerability allows an attacker who has access to the WBM to read and write settings-parameters of the device by sending specifically constructed requests without authentication on multiple WAGO PLCs in firmware versions up to FW07.
How severe is CVE-2021-34578?: CVE-2021-34578 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-34578 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-2021-34578?: CVE-2021-34578 primarily affects Wago 750-890/040-000 Firmware. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34578?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-34578 published?: CVE-2021-34578 was published on 2021-08-31 and last updated on 2026-06-17.

References

https://cert.vde.com/en-us/advisories/vde-2020-044

Affected products (12)

cpe:2.3:o:wago:750-890\/040-000_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-890\/025-001_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-890\/025-002_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-890\/025-000_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-832\/000-002_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-362_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-832_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-363_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-862_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-891_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-893_firmware:*:*:*:*:*:*:*:*

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