Massive Cyberattack on French Healthcare Software Exposes Personal Data of Up to 15 Million Patients

A significant cyberattack at the end of 2025 has compromised the personal data of between 11 to 15 million French patients, according to multiple reports. The cyberattack targeted Cegedim Santé's "Mon logiciel médical" (MLM) software, used by about 3,800 healthcare professionals across France.

Cegedim Santé confirmed the data breach, which involved unauthorized access to patients' personal administrative information such as names, birth dates, phone numbers, and postal addresses. Importantly, the company stated that structured medical records remained secure and were not accessed. However, a limited number of cases included sensitive details like doctors' annotations, sexual orientation, and health conditions. An online data sample comprised administrative information on nearly 300,000 patients, with only a small fraction containing sensitive information.

Estimates of affected individuals vary; France 2 suggests the breach impacts between 11 and 15 million patients, while a hacker claims access to data on 19 million people. Cegedim attributes the exposure to only around 1,500 practitioners using the MLM system, indicating a narrower scope. The breach was detected after anomalous software behavior was identified in late 2025.

Following discovery, Cegedim promptly reported the attack to the authorities, including lodging a complaint with the prosecutor's office and notifying the Commission Nationale de l'Informatique et des Libertés (CNIL). The Ministry of Health, which clarified that the breach was related to a private provider and not public healthcare systems, is actively monitoring the situation. Health Minister Stéphanie Rist requested a report from Cegedim on the incident’s causes and corrective measures to prevent future occurrences.

This unprecedented data breach underscores growing concerns over cybersecurity in the French healthcare sector and highlights challenges in protecting sensitive patient information amid increasing cyber threats.