Which versions of SIMATIC CN 4100 are affected by EUVD-2026-29423?

CVE-2026-22924 affects Siemens SIMATIC CN 4100 industrial control systems prior to version 5.0, enabling unauthenticated remote attackers to bypass authentication and exhaust system resources,…

How to fix or mitigate EUVD-2026-29423?

24 hours: Identify all SIMATIC CN 4100 devices in production and document current firmware versions; isolate any systems running versions before V5.0 from untrusted networks if immediate patching is not feasible. 7 days: Deploy firmware version 5.0 or later to all affected SIMATIC CN 4100 devices following Siemens SSA-032379 guidance; prioritize critical production systems. 30 days: Complete patch deployment across all SIMATIC CN 4100 infrastructure; conduct post-patch validation testing and document completion for compliance records.

SIMATIC CN 4100 EUVD-2026-29423

Q: What is the CVSS score of EUVD-2026-29423?

EUVD-2026-29423 has a CVSS 4.0 base score of 8.8 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

| CVE-2026-22924 HIGH

Missing Authentication for Critical Function (CWE-306)

2026-05-12 siemens

GHSA-9p8h-826j-wp3r

Authentication Bypass Denial Of Service Simatic Cn 4100

8.8

CVSS 4.0 · Vendor: siemens

Severity by source

Vendor (siemens) PRIMARY

8.8 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from Vendor (siemens) · only source for this CVE.

CVSS VectorVendor: siemens

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Updated

May 12, 2026 - 10:36 vuln.today

v2 (cvss_changed)

Re-analysis Queued

May 12, 2026 - 10:22 vuln.today

cvss_changed

Severity Changed

May 12, 2026 - 10:22 NVD

CRITICAL HIGH

CVSS changed

May 12, 2026 - 10:22 NVD

9.1 (CRITICAL) 8.8 (HIGH)

Analysis Generated

May 12, 2026 - 10:01 vuln.today

CVE Published

May 12, 2026 - 08:20 nvd

CRITICAL 9.1

DescriptionCVE.org

A vulnerability has been identified in SIMATIC CN 4100 (All versions < V5.0). The affected application does not properly restrict unauthenticated connections and is susceptible to resource exhaustion conditions. This could allow an attacker to disrupt normal operations or perform unauthorized actions, potentially impacting system availability and integrity.

AnalysisAI

Remote unauthenticated attackers can exhaust resources and bypass authentication controls in Siemens SIMATIC CN 4100 versions before V5.0, enabling denial of service conditions and unauthorized actions that compromise system availability and integrity. The vulnerability stems from improper connection validation (CWE-306), allowing network-based exploitation without any user interaction or privileges. Siemens has released V5.0 to address this flaw, documented in security advisory SSA-032379.

Technical ContextAI

SIMATIC CN 4100 is an industrial communication node used in Siemens automation environments for network connectivity and data exchange in operational technology (OT) networks. The vulnerability is rooted in CWE-306 (Missing Authentication for Critical Function), indicating the device fails to properly authenticate or validate incoming network connections before allocating resources or granting access to functionality. This class of flaw is common in embedded industrial devices where default configurations may prioritize availability over security controls. The CVSS 4.0 vector shows network-accessible attack surface (AV:N), no complexity barriers (AC:L), and no authentication gates (PR:N), combined with high integrity and availability impact (VI:H/VA:H), reflecting both the ease of exploitation and severity of consequences in industrial control system contexts.

RemediationAI

Update SIMATIC CN 4100 to version V5.0 or later as specified in Siemens security advisory SSA-032379 (https://cert-portal.siemens.com/productcert/html/ssa-032379.html). Until patching is complete, implement network segmentation to restrict access to SIMATIC CN 4100 devices exclusively from trusted management networks-block all unauthenticated external access using industrial firewalls or VLANs, noting this may complicate distributed monitoring scenarios. Deploy connection rate limiting at the network perimeter to mitigate resource exhaustion vectors, though this does not address the authentication bypass component. For critical production systems where immediate patching risks operational disruption, schedule maintenance windows and test V5.0 in staging environments first, as firmware updates on industrial control devices can require extended downtime and revalidation of connected systems.