What is this vulnerability?

Certain devices in the WAGO System I/O Field series activate an internal diagnostic capability during the initial startup sequence. This functionality is not formally documented and becomes accessible without authentication for a brief period in the early boot phase. During this window, an unauthenticated remote attacker can gain access to the internal system processes, resulting in full system compromise.

How it works

This is classified as CWE-912. In plain terms, an attacker could use this flaw in the affected product to gain access, disrupt service, or steal data — the exact impact depends on how it’s deployed in your environment.

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

Mitigations

• Apply the vendor’s security patch or update as soon as it’s available and tested.
• If no patch exists yet, apply the vendor’s temporary workaround.
• Limit network exposure of the affected system until it’s patched.
• Track the vendor advisory — disclosed vulnerabilities can move to active exploitation quickly.

Recommendations

• Confirm whether this vendor’s affected product is used anywhere in your environment.
• Patch internet-facing systems first, then internal ones.
• Prioritise by exposure and exploitability while a fix is scheduled.
• Subscribe to the vendor’s security advisories for earlier warning next time.