CVE-2025-40944

High

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.

SeverityHigh
CVSS7.5
Exploit probability—
ProductSIMATIC ET 200AL IM 157-1 PN
PublishedJan 13, 2026
First seenJan 13, 2026

How to fix

Update
  • Siemens SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants)V1.3 or later
  • Siemens SIMATIC ET 200SP IM 155-6 PN R1V6.0.1 or later
  • Siemens SIMATIC ET 200SP IM 155-6 PN/2 HFV4.2.5 or later
  • Siemens SIMATIC ET 200SP IM 155-6 PN/3 HFV4.2.2 or later
  • Siemens SIMATIC PN/PN CouplerV6.0.0 or later
  • Siemens SIPLUS ET 200SP IM 155-6 PN HFV4.2.5 or later
  • Siemens SIPLUS ET 200SP IM 155-6 PN HF T1 RAILV4.2.5 or later
  • Siemens SIPLUS ET 200SP IM 155-6 PN HF TX RAILV4.2.5 or later
  • Siemens SIPLUS NET PN/PN CouplerV6.0.0 or later

Affected products

ProductAffected versionsFixed in
Siemens SIMATIC ET 200AL IM 157-1 PN0—
Siemens SIMATIC ET 200MP IM 155-5 PN HFV4.2.0—
Siemens SIMATIC ET 200SP IM 155-6 MF HF0—
Siemens SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants)v < V1.3V1.3
Siemens SIMATIC ET 200SP IM 155-6 PN R1v < V6.0.1V6.0.1
Siemens SIMATIC ET 200SP IM 155-6 PN/2 HFV4.2.0 ≤ v < V4.2.5V4.2.5
Siemens SIMATIC ET 200SP IM 155-6 PN/3 HFv < V4.2.2V4.2.2
Siemens SIMATIC PN/MF Coupler0—
Siemens SIMATIC PN/PN Couplerv < V6.0.0V6.0.0
Siemens SIPLUS ET 200MP IM 155-5 PN HFV4.2.0—
Siemens SIPLUS ET 200MP IM 155-5 PN HF T1 RAILV4.2.0—
Siemens SIPLUS ET 200SP IM 155-6 PN HFV4.2.0 ≤ v < V4.2.5V4.2.5
Siemens SIPLUS ET 200SP IM 155-6 PN HF T1 RAILV4.2.0 ≤ v < V4.2.5V4.2.5
Siemens SIPLUS ET 200SP IM 155-6 PN HF TX RAILV4.2.0 ≤ v < V4.2.5V4.2.5
Siemens SIPLUS NET PN/PN Couplerv < V6.0.0V6.0.0

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CVE-2025-40944 · SIMATIC ET 200AL IM 157-1 PN · Dark Radar