CVE-2025-40797 is an out-of-bounds read vulnerability classified under CWE-125 found in Siemens SIMATIC PCS neo versions 4.1, 5.0, 6.0, and the User Management Component (UMC) versions prior to 2.15.1.3. The vulnerability arises from improper bounds checking in the UMC component, which is integrated into the PCS neo industrial process control system. An attacker can remotely exploit this flaw without any authentication or user interaction by sending specially crafted network requests to the vulnerable component. Exploitation results in a denial of service condition, likely causing the affected service or system to crash or become unresponsive, thereby impacting system availability. The CVSS v3.1 base score is 7.5, reflecting high severity due to network attack vector, no required privileges, and no user interaction, combined with a significant impact on availability. While confidentiality and integrity remain unaffected, the disruption of availability in industrial control systems can have severe operational consequences. Siemens has not yet published patches at the time of this report, and no exploits are known in the wild. The vulnerability affects all versions of PCS neo 4.1, 5.0, 6.0, and UMC prior to 2.15.1.3, making it broadly relevant to users of these products. Given the critical role of PCS neo in managing industrial processes, this vulnerability poses a significant risk to industrial environments if left unmitigated.

The primary impact of CVE-2025-40797 is a denial of service condition that can disrupt industrial process control systems running Siemens SIMATIC PCS neo. For European organizations, particularly those in manufacturing, energy, utilities, and critical infrastructure sectors, this can lead to operational downtime, production losses, and potential safety hazards. The vulnerability's ability to be exploited remotely without authentication increases the risk of widespread disruption, especially if attackers gain network access. Although confidentiality and integrity are not directly compromised, the loss of availability in industrial control environments can cascade into broader operational and economic impacts. European industries heavily reliant on Siemens PCS neo for automation and control are at risk of service interruptions that could affect supply chains and critical services. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score and ease of exploitation necessitate urgent attention.

1. Implement strict network segmentation to isolate PCS neo systems and the UMC component from general enterprise networks and the internet, limiting exposure to potential attackers. 2. Enforce access control lists (ACLs) and firewall rules to restrict inbound traffic to only trusted sources and necessary protocols targeting the PCS neo environment. 3. Monitor network traffic for unusual or malformed packets directed at the UMC component that could indicate exploitation attempts. 4. Apply Siemens security advisories and patches immediately once they become available to remediate the vulnerability. 5. Conduct regular vulnerability assessments and penetration testing focused on industrial control systems to identify and address weaknesses proactively. 6. Employ intrusion detection and prevention systems (IDS/IPS) tailored for industrial protocols to detect exploitation attempts. 7. Maintain up-to-date incident response plans specific to industrial control system disruptions to minimize downtime in case of an attack.