CVE-2025-40816 identifies a critical security vulnerability in Siemens LOGO! 12/24RCE series programmable logic controllers (PLCs), including all versions of LOGO! 12/24RCE, LOGO! 230RCE, LOGO! 24CE, LOGO! 24RCE, and their SIPLUS variants. The root cause is a missing authentication mechanism for certain critical functions within the device firmware, specifically those that handle network configuration changes. This flaw allows an unauthenticated remote attacker to manipulate the device's IP address without any authentication or user interaction. The manipulation of the IP address can cause the device to become unreachable on the network, effectively resulting in a denial-of-service (DoS) condition. The vulnerability is classified under CWE-306 (Missing Authentication for Critical Function), indicating that the device fails to verify the identity or permissions of entities requesting sensitive operations. The CVSS v3.1 base score is 7.6 (high severity), with attack vector being adjacent network (AV:A), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and impacts on confidentiality (C:L), integrity (I:L), and availability (A:H). Although no known exploits are currently reported in the wild, the vulnerability's nature and the critical role of these PLCs in industrial automation environments make it a significant threat. Siemens has not yet released patches, so affected organizations must rely on compensating controls. The vulnerability affects a broad range of Siemens LOGO! devices widely used in industrial control systems for small to medium automation tasks, including manufacturing, building automation, and infrastructure management.

The primary impact of CVE-2025-40816 is on the availability of affected Siemens LOGO! PLC devices. By allowing unauthenticated remote attackers to change the device's IP address, the vulnerability can cause the device to become unreachable, disrupting industrial automation processes that rely on these controllers. This can lead to production downtime, safety risks, and operational inefficiencies. The limited confidentiality and integrity impacts stem from the potential for unauthorized network configuration changes, which could be leveraged in multi-stage attacks. For European organizations, especially those in manufacturing, utilities, and critical infrastructure sectors that heavily use Siemens automation products, this vulnerability poses a significant operational risk. Disruption of PLCs can cascade into broader system failures or safety incidents. The lack of authentication also raises concerns about insider threats or lateral movement by attackers within industrial networks. Given Siemens' strong market presence in Europe, the vulnerability could affect a large number of installations, increasing the potential for widespread impact if exploited.

1. Siemens should prioritize releasing firmware updates or patches that implement proper authentication checks for critical functions, including network configuration changes. 2. Until patches are available, organizations must isolate affected PLCs on segmented, trusted networks with strict access controls to prevent unauthorized remote access. 3. Implement network monitoring and anomaly detection to identify unexpected changes in device IP addresses or unauthorized configuration attempts. 4. Use firewalls and access control lists (ACLs) to restrict communication to and from LOGO! devices only to authorized management stations. 5. Employ VPNs or secure tunnels for remote access to industrial control systems to reduce exposure to adjacent network attackers. 6. Conduct regular audits of device configurations and network topology to detect unauthorized modifications promptly. 7. Train operational technology (OT) personnel to recognize signs of network manipulation and enforce strong physical security to prevent local tampering. 8. Develop incident response plans specific to industrial control system disruptions to minimize downtime in case of exploitation.