McKesson confirmed on 28 August 2026 that attackers reached employee corporate accounts and, through them, third-party applications, taking data tied to a subset of customers in its Oncology & Multispecialty and Medical-Surgical businesses. Its formal notice of 8 September says the intrusion ran from 20 to 25 August and lists the categories involved, including medical information and, for some people, Social Security numbers. McKesson has still not said how many people are affected, and the 284 million figure circulating publicly is an attacker claim the company has never confirmed.
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