McKesson discloses breach after ShinyHunters claims patient data theft post, augustus 28, 2026september 4, 2026 Healthcare and pharmaceutical distribution giant McKesson has disclosed a cybersecurity incident involving unauthorized access to third-party applications and data theft, with the ShinyHunters extortion group claiming it stole 284 million patient data records. McKesson is a major U.S. healthcare company and pharmaceutical distributor that provides medicines, medical supplies, technology, and services to healthcare providers and pharmacies. CyberInsider first reported the breach earlier today, and McKesson later disclosed it in a Form 8-K filing with the U.S. Securities and Exchange Commission. McKesson discloses breach after ShinyHunters claims patient data theft: McKesson discloses breach after ShinyHunters claims patient data theft datalek 2026ShinyHunters