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5.1
MEDIUM CVSS 4.0
CVE-2025-40939
"Siemens SIMATIC CN 4100 USB Reboot Denial of Service"
Description

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.

INFO

Published Date :

Dec. 9, 2025, 4:17 p.m.

Last Modified :

Dec. 10, 2025, 9:35 p.m.

Remotely Exploit :

No

Source :

[email protected]
Affected Products

The following products are affected by CVE-2025-40939 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Siemens simatic_cn_4100
: Total Affected Vendor : 1 | Products : 1
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM MITRE-CVE
CVSS 3.1 MEDIUM [email protected]
CVSS 4.0 MEDIUM [email protected]
Solution
Update SIMATIC CN 4100 to V4.0.1 or later to address authentication bypass and DoS.
  • Update SIMATIC CN 4100 to V4.0.1 or later.
  • Restrict physical access to the device.
  • Disable unused USB ports if possible.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-40939.

URL Resource
https://cert-portal.siemens.com/productcert/html/ssa-416652.html Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-40939 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-40939 weaknesses.

CAPEC-19: Embedding Scripts within Scripts Embedding Scripts within Scripts CAPEC-441: Malicious Logic Insertion Malicious Logic Insertion CAPEC-478: Modification of Windows Service Configuration Modification of Windows Service Configuration CAPEC-479: Malicious Root Certificate Malicious Root Certificate CAPEC-502: Intent Spoof Intent Spoof CAPEC-503: WebView Exposure WebView Exposure CAPEC-536: Data Injected During Configuration Data Injected During Configuration CAPEC-546: Incomplete Data Deletion in a Multi-Tenant Environment Incomplete Data Deletion in a Multi-Tenant Environment CAPEC-550: Install New Service Install New Service CAPEC-551: Modify Existing Service Modify Existing Service CAPEC-552: Install Rootkit Install Rootkit CAPEC-556: Replace File Extension Handlers Replace File Extension Handlers CAPEC-558: Replace Trusted Executable Replace Trusted Executable CAPEC-562: Modify Shared File Modify Shared File CAPEC-563: Add Malicious File to Shared Webroot Add Malicious File to Shared Webroot CAPEC-564: Run Software at Logon Run Software at Logon CAPEC-578: Disable Security Software Disable Security Software

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-40939 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-40939 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Dec. 10, 2025

    Action Type Old Value New Value
    CPE Configuration
    Added Reference Type Siemens AG: https://cert-portal.siemens.com/productcert/html/ssa-416652.html Types: Vendor Advisory
  • New CVE Received by [email protected]

    Dec. 09, 2025

    Action Type Old Value New Value
    Added Description 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.
    Added CVSS V4.0 AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
    Added CVSS V3.1 AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    Added CWE CWE-284
    Added Reference https://cert-portal.siemens.com/productcert/html/ssa-416652.html
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 5.1
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability
Base CVSS Score: 4.6
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact