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Vulnerability record · CVE-2021-34578 · published 31 August 2021

CVE-2021-34578: Wago 750-890\/040-000 firmware improper authentication vulnerability

Wago · 750 890\/040 000 Firmware

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.

8.1 CVSS 3.1 High EPSS 0.96% · top 39.1% CWE-287 · Improper authentication
8.1CVSS 3.1 base score, v2 6.8
0.96%EPSS exploitation probability, 30 days
NoNot in CISA KEV
12Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

12 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cert.vde.com/en-us/advisories/vde-2020-044 Third Party Advisory
https://cert.vde.com/en-us/advisories/vde-2020-044 Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-30189Wago 750-893 firmware out-of-bounds write vulnerabilityCODESYS V2 Web-Server before 1.1.9.20 has a Stack-based Buffer Overflow.EPSS 1.3%9.8CVE-2021-30192Wago 750-893 firmware vulnerabilityCODESYS V2 Web-Server before 1.1.9.20 has an Improperly Implemented Security Check.EPSS 1.2%9.8CVE-2021-30190Wago 750-893 firmware missing authentication for critical function vulnerabilityCODESYS V2 Web-Server before 1.1.9.20 has Improper Access Control.EPSS 1.4%9.8CVE-2021-30188Wago 750-893 firmware out-of-bounds write vulnerabilityCODESYS V2 runtime system SP before 2.4.7.55 has a Stack-based Buffer Overflow.EPSS 1.3%9.8CVE-2021-30193Wago 750-893 firmware out-of-bounds write vulnerabilityCODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Write.EPSS 1.2%9.1CVE-2021-34584Wago 750-823 firmware vulnerabilityCrafted web server requests can be utilised to read partial stack or heap memory or may trigger a denial-of- service condition due to a crash in the …EPSS 1.1%9.1CVE-2021-30194Wago 750-893 firmware out-of-bounds read vulnerabilityCODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Read.EPSS 1.2%9.1CVE-2020-12506Wago 750-362 firmware missing authentication for critical function vulnerabilityImproper Authentication vulnerability in WAGO 750-8XX series with FW version <= FW03 allows an attacker to change the settings of the devices by send…EPSS 1.5%

Source: NIST National Vulnerability Database (record CVE-2021-34578), CISA KEV, FIRST EPSS (scores of 2026-10-14). This page is refreshed as NVD updates the record.