WAGO I/O-CHECK Missing Authentication For Critical Function (CVE-2019-5077)

critical Tenable OT Security Plugin ID 500814


The remote OT asset is affected by a vulnerability.


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.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.


The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at CISA.gov.

WAGO recommends updating to the latest firmware, FW 15 or above. WAGO has identified the following specific workarounds and mitigations users can apply to reduce the risk:

- The I/O-Check service protocol is only needed during installation and commissioning, not during normal operations.
- It is highly recommended to disable IP Port 6626 after commissioning.
- Disable unused TCP/UDP-ports.
- Restrict network access to the device.
- Do not directly connect the device to the Internet.

See Also



Plugin Details

Severity: Critical

ID: 500814

Version: 1.4

Type: remote

Family: Tenable.ot

Published: 2/14/2023

Updated: 3/4/2024

Supported Sensors: Tenable OT Security

Risk Information


Risk Factor: Medium

Score: 5.2


Risk Factor: High

Base Score: 8.5

Temporal Score: 6.3

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:C

CVSS Score Source: CVE-2019-5077


Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:wago:pfc_100_firmware:03.00.39%2812%29, cpe:/o:wago:pfc_200_firmware:03.00.39%2812%29, cpe:/o:wago:pfc_200_firmware:03.01.07%2813%29

Required KB Items: Tenable.ot/Wago

Exploit Ease: No known exploits are available

Patch Publication Date: 12/18/2019

Vulnerability Publication Date: 12/18/2019

Reference Information

CVE: CVE-2019-5077

CWE: 306