CVE-2020-27252 is a high-severity vulnerability affecting the Medtronic MyCareLink Smart Model 25000 Patient Reader, a medical device used by patients to communicate with implantable cardiac devices. The vulnerability arises from a Time-of-check to Time-of-use (TOCTOU) race condition in the device's firmware update mechanism. Specifically, the software update system does not properly verify the authenticity of firmware before execution, allowing an attacker to upload and execute unsigned firmware remotely. This flaw enables remote code execution on the Patient Reader without requiring privileges or prior authentication, although user interaction is necessary to initiate the update process. The vulnerability impacts all versions of the affected product. The CVSS v3.1 base score is 8.8, reflecting high impact on confidentiality, integrity, and availability, with a scope change due to potential control over the device. Exploitation could lead to full compromise of the Patient Reader, potentially allowing attackers to manipulate device behavior, disrupt patient monitoring, or interfere with communication to implantable cardiac devices. Although no known exploits are reported in the wild, the critical nature of the device and the vulnerability's characteristics make it a significant threat. The lack of available patches at the time of disclosure further elevates risk. The CWE-367 classification highlights the race condition nature of the flaw, emphasizing the timing window where verification and execution are not properly synchronized, leading to exploitation opportunities.

For European healthcare organizations, this vulnerability poses a serious risk to patient safety and data security. Compromise of the Patient Reader could result in unauthorized control or disruption of cardiac device monitoring, potentially endangering patients' lives. Confidential patient health information could be exposed or manipulated, violating GDPR and other data protection regulations. The availability of the device could be impacted, leading to interruptions in critical medical monitoring and treatment. Healthcare providers relying on Medtronic devices must consider the operational impact, including potential liability and reputational damage. Given the remote exploitation vector, attackers could target healthcare infrastructure from outside the network perimeter, complicating traditional defense strategies. The vulnerability also raises concerns about supply chain security and device lifecycle management within European medical institutions.

Immediate mitigation should focus on restricting network access to the Patient Reader devices, implementing strict network segmentation to isolate them from general IT infrastructure and the internet. Healthcare providers should enforce strict user interaction policies to prevent unauthorized firmware updates, including training staff and patients on recognizing suspicious update prompts. Monitoring network traffic for anomalous firmware update attempts can help detect exploitation attempts. Since no patches are available, organizations should engage with Medtronic for firmware updates or advisories and consider temporary device usage restrictions or alternative monitoring solutions where feasible. Implementing multi-factor authentication or additional verification layers for firmware updates, if supported, can reduce risk. Regular audits of device configurations and update logs are recommended to identify unauthorized activities. Finally, integrating these devices into broader medical device management and incident response frameworks will improve preparedness and response capabilities.