Is CVE-2025-40939 in the CISA KEV catalog?

No. CVE-2025-40939 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-40939?

CVE-2025-40939 has a CVSS v3 base score of 4.6 (MEDIUM).

What is the EPSS score for CVE-2025-40939?

CVE-2025-40939 has an EPSS score of 0.18% (8th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-40939?

Upgrade simatic cn 4100 firmware to 4.0.1 or later.

CVE & CISA-KEV Catalog

CVE-2025-40939

MEDIUM

4.6

CVSS v3

NVD

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.

CWE-284Improper Access Control

How to fix

Remediation Available

simatic cn 4100 firmwareNVD

Affected:< 4.0.1Fixed in:4.0.1CVE-2025-40939derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorPhysical

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

0.18%probability of exploitation in 30 days

8thpercentile

Low risk: more likely to be exploited than 8% of all known CVEs.

References

Vendor Advisory1

cert-portal.siemens.com

Related Vulnerabilities

Other CWE-284 (Improper Access Control) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-27350	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2019-1653	High	7.5	100%	KEV	-
CVE-2023-23752	Medium	5.3	100%	KEV	Fix
CVE-2023-29298	High	7.5	100%	KEV	-
CVE-2023-38205	High	7.5	100%	KEV	-
CVE-2024-27348	Critical	9.8	99%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-16.