How severe is CVE-2025-40944?

CVE-2025-40944 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-40944 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-40944?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-40944 have an EU (EUVD) identifier?

Yes. CVE-2025-40944 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2359.

When was CVE-2025-40944 published?

CVE-2025-40944 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2025-40944

CVE-2025-40944 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2359
Weakness: CWE-400
Published: 2026-01-13
Last modified: 2026-06-17

Description

A vulnerability has been identified in SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0) (All versions), SIMATIC ET 200MP IM 155-5 PN HF (6ES7155-5AA00-0AC0) (All versions >= V4.2.0), SIMATIC ET 200SP IM 155-6 MF HF (6ES7155-6MU00-0CN0) (All versions), SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) (All versions < V1.3), SIMATIC ET 200SP IM 155-6 PN R1 (6ES7155-6AU00-0HM0) (All versions < V6.0.1), SIMATIC ET 200SP IM 155-6 PN/2 HF (6ES7155-6AU01-0CN0) (All versions >= V4.2.0 < V4.2.5), SIMATIC ET 200SP IM 155-6 PN/3 HF (6ES7155-6AU30-0CN0) (All versions < V4.2.2), SIMATIC PN/MF Coupler (6ES7158-3MU10-0XA0) (All versions), SIMATIC PN/PN Coupler (6ES7158-3AD10-0XA0) (All versions < V6.0.0), SIPLUS ET 200MP IM 155-5 PN HF (6AG1155-5AA00-2AC0) (All versions >= V4.2.0), SIPLUS ET 200MP IM 155-5 PN HF (6AG1155-5AA00-7AC0) (All versions >= V4.2.0), SIPLUS ET 200MP IM 155-5 PN HF T1 RAIL (6AG2155-5AA00-1AC0) (All versions >= V4.2.0), SIPLUS ET 200SP IM 155-6 PN HF (6AG1155-6AU01-2CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF (6AG1155-6AU01-7CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF T1 RAIL (6AG2155-6AU01-1CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF TX RAIL (6AG2155-6AU01-4CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS NET PN/PN Coupler (6AG2158-3AD10-4XA0) (All versions < V6.0.0). Affected devices do not properly handle S7 protocol session disconnect requests. When receiving a valid S7 protocol Disconnect Request (COTP DR TPDU) on TCP port 102, the devices enter an improper session state. This could allow an attacker to cause the device to become unresponsive, leading to a denial-of-service condition that requires a power cycle to restore normal operation.

Frequently asked questions

What is CVE-2025-40944?: A vulnerability has been identified in SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0) (All versions), SIMATIC ET 200MP IM 155-5 PN HF (6ES7155-5AA00-0AC0) (All versions >= V4.2.0), SIMATIC ET 200SP IM 155-6 MF HF (6ES7155-6MU00-0CN0) (All versions), SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) (All versions < V1.3), SIMATIC ET 200SP IM 155-6 PN R1 (6ES7155-6AU00-0HM0) (All versions < V6.0.1), SIMATIC ET 200SP IM 155-6 PN/2 HF (6ES7155-6AU01-0CN0) (All versions >= V4.2.0 < V4.2.5), SIMATIC ET 200SP IM 155-6 PN/3 HF (6ES7155-6AU30-0CN0) (All versions < V4.2.2), SIMATIC PN/MF Coupler (6ES7158-3MU10-0XA0) (All versions), SIMATIC PN/PN Coupler (6ES7158-3AD10-0XA0) (All versions < V6.0.0), SIPLUS ET 200MP IM 155-5 PN HF (6AG1155-5AA00-2AC0) (All versions >= V4.2.0), SIPLUS ET 200MP IM 155-5 PN HF (6AG1155-5AA00-7AC0) (All versions >= V4.2.0), SIPLUS ET 200MP IM 155-5 PN HF T1 RAIL (6AG2155-5AA00-1AC0) (All versions >= V4.2.0), SIPLUS ET 200SP IM 155-6 PN HF (6AG1155-6AU01-2CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF (6AG1155-6AU01-7CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF T1 RAIL (6AG2155-6AU01-1CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS ET 200SP IM 155-6 PN HF TX RAIL (6AG2155-6AU01-4CN0) (All versions >= V4.2.0 < V4.2.5), SIPLUS NET PN/PN Coupler (6AG2158-3AD10-4XA0) (All versions < V6.0.0). Affected devices do not properly handle S7 protocol session disconnect requests. When receiving a valid S7 protocol Disconnect Request (COTP DR TPDU) on TCP port 102, the devices enter an improper session state. This could allow an attacker to cause the device to become unresponsive, leading to a denial-of-service condition that requires a power cycle to restore normal operation.
How severe is CVE-2025-40944?: CVE-2025-40944 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-40944 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-40944?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-40944 have an EU (EUVD) identifier?: Yes. CVE-2025-40944 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2359.
When was CVE-2025-40944 published?: CVE-2025-40944 was published on 2026-01-13 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/html/ssa-674753.html

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