CVE-2025-59668 identifies a NULL pointer dereference vulnerability in the Central Monitor CNS-6201 produced by NIHON KOHDEN CORPORATION, affecting multiple firmware versions (01-03, 01-04, 01-05, 01-06, 02-10, 02-11, and 02-40). The vulnerability arises during the processing of a crafted UDP packet, which causes the device software to dereference a NULL pointer, leading to an abnormal termination or crash of the monitoring device. This type of fault results in a denial-of-service (DoS) condition, rendering the device unavailable for patient monitoring. The vulnerability is remotely exploitable without requiring any privileges or user interaction, increasing the risk of exploitation. The CVSS v3.0 score of 7.5 reflects a high severity primarily due to the ease of remote exploitation and the impact on availability. No confidentiality or integrity impacts are noted, and no known exploits have been reported in the wild as of the publication date. The affected product is a critical medical device used in healthcare settings to monitor patient vital signs, making availability crucial for patient safety. The lack of patches at the time of disclosure necessitates interim mitigations such as network filtering and segmentation to prevent malicious UDP packets from reaching the device. The vulnerability was assigned and published by JPCERT, indicating coordinated disclosure and monitoring.

The primary impact of CVE-2025-59668 is a denial-of-service condition that disrupts the availability of the Central Monitor CNS-6201 devices. For European healthcare organizations, this can translate into critical interruptions in patient monitoring, potentially delaying medical responses and jeopardizing patient safety. Hospitals and clinics relying on these devices may experience operational downtime, increased workload on medical staff, and the need for manual monitoring alternatives. Although the vulnerability does not affect confidentiality or integrity, the loss of availability in medical monitoring equipment is a significant risk in clinical environments. Additionally, the remote and unauthenticated nature of the exploit increases the threat surface, especially if the devices are accessible from less secure network segments or exposed to the internet. The absence of known exploits in the wild reduces immediate risk but does not eliminate the potential for future attacks. European healthcare providers must consider the impact on compliance with medical device regulations and patient safety standards, which mandate high availability and reliability of such equipment.

1. Apply official patches or firmware updates from NIHON KOHDEN CORPORATION as soon as they become available to address the NULL pointer dereference vulnerability directly. 2. Implement strict network segmentation to isolate CNS-6201 devices from general network traffic, limiting exposure to untrusted sources. 3. Deploy firewall rules or intrusion prevention systems (IPS) to block or filter unexpected or malformed UDP packets targeting the devices, especially from external or untrusted networks. 4. Monitor network traffic for unusual UDP packet patterns that could indicate exploitation attempts. 5. Restrict remote access to the devices to authorized personnel only, using VPNs or secure management channels. 6. Conduct regular security assessments and vulnerability scans on medical device networks to identify and remediate exposures. 7. Develop incident response plans specific to medical device availability issues to ensure rapid recovery and continuity of patient monitoring. 8. Coordinate with device vendors and healthcare cybersecurity teams to stay informed about updates and advisories related to this vulnerability.