CVE-2025-40815 is a classic buffer overflow vulnerability (CWE-120) identified in multiple Siemens LOGO! PLC models, including LOGO! 12/24RCE, LOGO! 230RCE, LOGO! 24CE, and their SIPLUS variants. The vulnerability stems from inadequate validation of TCP packet structures within several internal methods of the affected devices. Specifically, the devices fail to properly check the size of input data during buffer copy operations, allowing an attacker to overflow buffers. This overflow can overwrite the instruction counter, enabling arbitrary code execution on the device. The vulnerability affects all versions of the listed models, indicating a systemic issue in the TCP packet handling code. Exploitation requires network access and high privileges (PR:H), but no user interaction is needed. The CVSS v3.1 base score is 7.2 (high), reflecting the network attack vector, low attack complexity, requirement for privileges, and the potential for full confidentiality, integrity, and availability compromise. Siemens has published the vulnerability but no patches or exploits are currently reported. The affected devices are widely used in industrial automation for controlling machinery, building systems, and other critical processes, making this vulnerability a significant risk for operational technology environments.

For European organizations, the impact of CVE-2025-40815 could be severe, particularly in sectors relying on Siemens LOGO! PLCs for automation and control. Successful exploitation could allow attackers to execute arbitrary code on PLCs, leading to manipulation or disruption of industrial processes. This threatens operational continuity, safety, and data confidentiality. Potential consequences include production downtime, physical damage to equipment, safety hazards to personnel, and loss of sensitive operational data. Given the network-based attack vector, attackers could remotely compromise devices if network segmentation and access controls are insufficient. The high integrity and availability impact is critical for industries such as manufacturing, energy, transportation, and building management systems prevalent across Europe. Additionally, disruption of these systems could have cascading effects on supply chains and critical infrastructure. The lack of known exploits currently provides a window for mitigation, but the vulnerability’s nature makes it attractive for advanced persistent threats targeting industrial environments.

1. Apply Siemens-provided patches immediately once available to address the buffer overflow vulnerability. 2. Restrict network access to affected PLCs by implementing strict firewall rules and network segmentation, isolating PLCs from general IT networks and the internet. 3. Employ deep packet inspection and anomaly detection systems to identify and block malformed TCP packets targeting PLCs. 4. Enforce strong authentication and access control policies to limit privileged user access, as exploitation requires high privileges. 5. Regularly audit and monitor network traffic to and from PLCs for suspicious activity. 6. Implement network intrusion detection systems (NIDS) tailored for industrial protocols to detect exploitation attempts. 7. Develop and test incident response plans specific to industrial control system compromises. 8. Educate operational technology (OT) personnel about this vulnerability and safe handling of Siemens LOGO! devices. 9. Consider deploying virtual patching or compensating controls if immediate patching is not feasible. 10. Maintain up-to-date asset inventories to quickly identify affected devices and prioritize remediation.