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Pfc 200 FirmwareOperating system · Wago

CVE-2019-5077

CRITICAL · 9.1 CVSS v3.1 Published 2019-12-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A denial-of-service vulnerability exists in the iocheckd service 'I/O-Check' functionality of WAGO PFC 100 and PFC 200 PLCs. An attacker can send specially crafted unauthenticated packets to trigger this vulnerability, causing the device to enter an error state where it completely ceases all network communications. This affects specific firmware versions on both the PFC 100 and PFC 200 platforms.

MitigationApply vendor-released firmware patches for WAGO PFC 100 and PFC 200 devices; if patches are unavailable, implement network segmentation and firewall rules to restrict unauthorized access to the iocheckd service.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Pfc 200 FirmwareOperating system
Affected:= 03.00.39\(12\)= 03.01.07\(13\)
Pfc 100 FirmwareOperating system
Affected:= 03.00.39\(12\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Access the device's web interface, CLI, or use SNMP to determine if the device is a WAGO PFC 100 or PFC 200 PLC. Check the device's system information or model identification page.
    Affected if The device is not a WAGO PFC 100 or PFC 200, as this CVE only affects those specific platforms.
  2. Check PFC 200 firmware version
    For PFC 200 devices, navigate to the web interface (System -> Firmware) or use the command line with 'fw_printenv' or check /etc/version to retrieve the installed firmware version. Compare against affected versions 03.00.39(12) and 03.01.07(13).
    Affected if The firmware version exactly matches 03.00.39(12) or 03.01.07(13) on a PFC 200.
  3. Check PFC 100 firmware version
    For PFC 100 devices, navigate to the web interface (System -> Firmware) or use the command line with 'fw_printenv' or check /etc/version to retrieve the installed firmware version. Compare against affected version 03.00.39(12).
    Affected if The firmware version exactly matches 03.00.39(12) on a PFC 100.
  4. Verify iocheckd service exposure
    Check network configuration to determine if the iocheckd service (port 6626/TCP typically) is exposed to untrusted networks. Review firewall rules, network segmentation, and ACLs governing access to the device's ports.
    Affected if The iocheckd service port is accessible from untrusted network segments, as exploitation requires sending packets to this service.

A user is affected if they have a WAGO PFC 100 (firmware 03.00.39(12)) or PFC 200 (firmware 03.00.39(12) or 03.01.07(13)) with the iocheckd service exposed to network attackers.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor-released firmware patches for WAGO PFC 100 and PFC 200 devices; if patches are unavailable, implement network segmentation and firewall rules to restrict unauthorized access to the iocheckd service.

Fix this in Pfc 200 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-5077 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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