Vulnerability in Siemens Simatic Cn 4100

CVE-2025-40939

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (11.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-40939: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-40939?
CVE-2025-40939 is a medium-severity vulnerability in Siemens Simatic Cn 4100, classified under Improper Access Control. CVSS score: 4.6/10. Published 2025-12-09.
How severe is CVE-2025-40939?
Medium severity. CVSS v3 base score is 4.6 out of 10.