External risk intelligence

SIMATIC CN 4100 Firmware Sensitive Information Disclosure

CVE advisorySeverity: CRITICAL (CVSS 9.2)

CVE-2025-40938

The affected product, SIMATIC CN 4100, is an industrial communication gateway typically deployed within restricted operational technology (OT) or industrial control system (ICS) networks. While the device is network-connected, it is designed for internal industrial infrastructure and is generally not intended for direct exposure to the public internet in standard deployment patterns.

Siemens Simatic Cn 4100 Firmware

before 4.0.1

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists in SIMATIC CN 4100 devices, where sensitive information is stored in the firmware. This could potentially allow unauthorized access and misuse of this data, impacting the device's confidentiality, integrity, and availability. The main concern is confirming relevance and exposure within your industrial control systems.

Sensitive information stored in device firmware.
Potential for unauthorized access and data misuse.
Confirm relevance and exposure in your environment.

Attack Path

How an attacker could exploit the issue

An attacker could gain access to sensitive information stored within the SIMATIC CN 4100 firmware. This could be achieved without needing any special privileges or user interaction, as long as the device is exposed to a network. Once accessed, this information could be misused, potentially compromising the device's confidentiality, integrity, and availability.

Network access is required.
Sensitive information is exposed in firmware.
Risk of confidentiality, integrity, availability loss.

Live Threat

Current exploitation, exposure, and threat context

Sensitive information stored within the SIMATIC CN 4100 firmware could be accessed and misused, potentially affecting the device's confidentiality, integrity, and availability under supported conditions.

Sensitive firmware information at risk.
Attacker may access stored sensitive information.
Device confidentiality, integrity, and availability impacted.

Operational Fix

Recommended remediation, mitigation, and detection steps

The SIMATIC CN 4100 is an industrial communication gateway, suggesting that ownership likely falls to an Industrial Control System (ICS) or Operational Technology (OT) infrastructure team. The first practical step is to identify all instances of this device within the network, assess their business criticality and network exposure, and then determine the accountable owner for remediation planning.

ICS/OT teams should own this issue.
Verify device criticality and reachability.
Plan coordinated remediation by asset owner.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the SIMATIC CN 4100?

The SIMATIC CN 4100 is an industrial communication gateway developed by Siemens. It acts as a bridge within industrial control environments, enabling secure data exchange and connectivity between different automation networks and higher-level systems to manage production processes.

What does CWE-798 mean for CVE-2025-40938?

This CVE involves a vulnerability classified as CWE-798, which refers to the use of hard-coded credentials. In this specific case, the firmware stores sensitive information directly within the device's code. An attacker who gains access to this data could potentially use it to compromise the device, threatening its core confidentiality, integrity, and availability.

How can an attacker trigger this vulnerability?

An attacker needs network access to the device to exploit this firmware issue. Because the sensitive information is stored statically, the vulnerability does not require any specific user interaction or pre-existing elevated privileges. If the device is reachable over the network, it is potentially susceptible to unauthorized access attempts.

Should I be concerned if my SIMATIC CN 4100 is internal?

According to Halo Surface Signal, this device is typically used in restricted industrial or operational technology networks rather than being directly connected to the public internet. While the vulnerability is reachable over a network, its overall risk is often mitigated by the fact that these gateways are usually intended for segmented, internal industrial infrastructure.

What should I do first to manage this CVE?

Start by identifying every SIMATIC CN 4100 device within your organization. Coordinate with your industrial control or operations technology teams to confirm where these devices are located, assess their current network exposure, and prioritize remediation planning for any systems that have been updated to versions prior to V4.0.1.

References

cert-portal.siemens.com/productcert/html/ssa-416652.html

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.