DoS via S7 Disconnect on Siemens SIMATIC ET 200 series <v6.0
CVE-2025-40944 Published on January 13, 2026

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), 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), SIPLUS ET 200SP IM 155-6 PN HF (6AG1155-6AU01-7CN0) (All versions >= V4.2.0), SIPLUS ET 200SP IM 155-6 PN HF T1 RAIL (6AG2155-6AU01-1CN0) (All versions >= V4.2.0), SIPLUS ET 200SP IM 155-6 PN HF TX RAIL (6AG2155-6AU01-4CN0) (All versions >= V4.2.0), 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.

NVD

Weakness Type

What is a Resource Exhaustion Vulnerability?

The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

CVE-2025-40944 has been classified to as a Resource Exhaustion vulnerability or weakness.


Affected Versions

Siemens SIMATIC ET 200AL IM 157-1 PN: Siemens SIMATIC ET 200MP IM 155-5 PN HF: Siemens SIMATIC ET 200SP IM 155-6 MF HF: Siemens SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants): Siemens SIMATIC ET 200SP IM 155-6 PN R1: Siemens SIMATIC ET 200SP IM 155-6 PN/2 HF: Siemens SIMATIC ET 200SP IM 155-6 PN/3 HF: Siemens SIMATIC PN/MF Coupler: Siemens SIMATIC PN/PN Coupler: Siemens SIPLUS ET 200MP IM 155-5 PN HF: Siemens SIPLUS ET 200MP IM 155-5 PN HF: Siemens SIPLUS ET 200MP IM 155-5 PN HF T1 RAIL: Siemens SIPLUS ET 200SP IM 155-6 PN HF: Siemens SIPLUS ET 200SP IM 155-6 PN HF: Siemens SIPLUS ET 200SP IM 155-6 PN HF T1 RAIL: Siemens SIPLUS ET 200SP IM 155-6 PN HF TX RAIL: Siemens SIPLUS NET PN/PN Coupler:

Exploit Probability

EPSS
0.02%
Percentile
4.51%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.