5.1

CVE-2025-40939: siemens simatic_cn_4100_firmware Improper Access Control

CVSS: 5.1v4.0MediumAnalyzed
Published 09-12-2025Last modified 09-12-2025
Open JSON

Vulnerability summary

CVE-2025-40939 is a medium (CVSS 5.1) Improper Access Control vulnerability in siemens simatic_cn_4100_firmware. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 10.9% of scored vulnerabilities.

Overall risk
20/100
0100
Low · default modelHow is this calculated?
CVSS score
5.1/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.21%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 09-12-2025
    PublishedVulnerability first disclosed.
  2. 09-12-2025
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.21%

Chance of exploitation in the next 30 days

Percentile

11%

Versus all other CVEs

30-day change

0.00 pp

From 0.21% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.21%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Siemens1 product

1 vendor · 1 product

References

1 links