CyberSecBulletin
CVE-2025-40944NVD status: Deferred

SIMATIC ET 200AL IM 157-1 PN: Uncontrolled Resource Consumption

Published Updated By the CyberSecBulletin desk

CVE-2025-40944 is a high-severity uncontrolled resource consumption vulnerability in SIMATIC ET 200AL IM 157-1 PN from Siemens, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SIMATIC ET 200AL IM 157-1 PN versions: all versions. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) to V1.3 or a later version.
  2. Update SIMATIC ET 200SP IM 155-6 PN R1 to V6.0.1 or a later version.
  3. Update SIMATIC ET 200SP IM 155-6 PN/2 HF to V4.2.5 or a later version.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SiemensSIMATIC ET 200AL IM 157-1 PNall versionsNot stated
SiemensSIMATIC ET 200MP IM 155-5 PN HFV4.2.0 and laterNot stated
SiemensSIMATIC ET 200SP IM 155-6 MF HFall versionsNot stated
SiemensSIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants)before V1.3V1.3
SiemensSIMATIC ET 200SP IM 155-6 PN R1before V6.0.1V6.0.1
SiemensSIMATIC ET 200SP IM 155-6 PN/2 HFV4.2.0 up to, but not including, V4.2.5V4.2.5
SiemensSIMATIC ET 200SP IM 155-6 PN/3 HFbefore V4.2.2V4.2.2
SiemensSIMATIC PN/MF Couplerall versionsNot stated
SiemensSIMATIC PN/PN Couplerbefore V6.0.0V6.0.0
SiemensSIPLUS ET 200MP IM 155-5 PN HFV4.2.0 and laterNot stated
SiemensSIPLUS ET 200MP IM 155-5 PN HF T1 RAILV4.2.0 and laterNot stated
SiemensSIPLUS ET 200SP IM 155-6 PN HFV4.2.0 up to, but not including, V4.2.5V4.2.5
SiemensSIPLUS ET 200SP IM 155-6 PN HF T1 RAILV4.2.0 up to, but not including, V4.2.5V4.2.5
SiemensSIPLUS ET 200SP IM 155-6 PN HF TX RAILV4.2.0 up to, but not including, V4.2.5V4.2.5
SiemensSIPLUS NET PN/PN Couplerbefore V6.0.0V6.0.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (siemens.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.7HighCNA (siemens.com)
CVSS 3.17.5HighCNA (siemens.com)

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource.

How developers prevent this class of flaw

  • Ensure that protocols have specific limits of scale placed on them.
  • Ensure that all failures in resource allocation place the system into a safe posture.

More Uncontrolled Resource Consumption vulnerabilities (CWE-400)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in SIMATIC ET 200AL IM 157-1 PN

All SIMATIC ET 200AL IM 157-1 PN vulnerabilities

Recent Uncontrolled Resource Consumption vulnerabilities

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