CVE intelligence and bounded remediation

CVE-2021-34578 — Wago 750-890/040-000 Firmware security vulnerability

Critical CVSS 9.8

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.

Severity
Critical
CVSS
9.8 (3.1)
Published
2021-08-31
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-287

Affected products

  • wago / 750-890/040-000_firmware
  • wago / 750-890/025-001_firmware
  • wago / 750-890/025-002_firmware
  • wago / 750-890/025-000_firmware
  • wago / 750-832/000-002_firmware
  • wago / 750-362_firmware

Showing 6 representative product identities from 12 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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