PatchTheCEVCVE-2025-40939: A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1)
19
Routine
MEDIUM 4.6UPGRADE
CVE-2025-40939 is a medium-severity flaw (CVSS 4.6) affecting simatic cn 4100 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Risk facts
| CVSS score | 4.6 (Medium) |
| Attack vector | Physical |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.2% (top 89%) |
| CISA exploited list | No |
| Weakness | CWE-284 |
| Published | 2025-12-09 |
| Last modified | 2026-10-23 |
Publisher (CNA): Siemens AG · Vendor: siemens
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
siemens simatic cn 4100 firmware UPGRADE
Affected: < 4.0.1
Fixed in: 4.0.1
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Related CVEs
- CVE-2025-40937 HIGH 8.3 UPGRADE A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1)
- CVE-2025-40938 HIGH 8.1 UPGRADE A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1)
- CVE-2025-40940 MEDIUM 4.9 UPGRADE A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1)
- CVE-2025-40941 MEDIUM 4.3 UPGRADE A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1)
- CVE-2025-39682 CRITICAL 9.8 EXPLOITED UPGRADE MITIGATE Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability