CVE intelligence and bounded remediation

CVE-2019-5077 — Wago Pfc 200 Firmware security vulnerability

Critical CVSS 9.1

An exploitable denial-of-service vulnerability exists in the iocheckd service ‘’I/O-Chec’’ functionality of WAGO PFC 200 Firmware versions 03.01.07(13) and 03.00.39(12), and WAGO PFC 100 Firmware version 03.00.39(12). A specially crafted set of packets can cause a denial of service, resulting in the device entering an error state where it ceases all network communications. An attacker can send unauthenticated packets to trigger this vulnerability.

Severity
Critical
CVSS
9.1 (3.1)
Published
2019-12-18
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-306

Affected products

  • wago / pfc_200_firmware / 03.00.39(12)
  • wago / pfc_200_firmware / 03.01.07(13)
  • wago / pfc_100_firmware / 03.00.39(12)

Matched remediation archetype

Authentication bypass and missing authentication

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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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