CVE-2025-40939: Medium severity Siemens SIMATIC CN 4100 vulnerability

Published Dec 9, 2025
·
Updated

A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected device contains a USB port which allows unauthenticated connections. This could allow an attacker with physical access to the device to trigger reboot that could cause denial of service condition.

Affected Software

3 affected components
Siemens SIMATIC CN 4100<4.0.1
All of the following
Siemens Simatic Cn 4100 Firmware<4.0.1
Siemens SIMATIC CN 4100

Event History

Dec 9, 2025
CVE Published
via MITRE·10:44 AM
Data Sourced
via MITRE·10:44 AM
DescriptionSeverityWeakness
Data Sourced
via NVD·04:17 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2025-40939?

CVE-2025-40939 has a high severity rating due to the potential for denial of service via unauthenticated physical access.

2

How do I fix CVE-2025-40939?

To mitigate CVE-2025-40939, upgrade the SIMATIC CN 4100 to version 4.0.1 or higher.

3

What is affected by CVE-2025-40939?

CVE-2025-40939 affects all versions of the Siemens SIMATIC CN 4100 that are below version 4.0.1.

4

What type of access is required to exploit CVE-2025-40939?

Exploitation of CVE-2025-40939 requires physical access to the affected device's USB port.

5

What is the impact of CVE-2025-40939?

The impact of CVE-2025-40939 can lead to a denial of service condition through unauthorized rebooting of the device.

Contact

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