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McKesson data theft and service disruption

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Incident date

McKesson discovered unauthorized access to third-party applications on August 25, 2026, and confirmed exfiltration of data associated with a subset of customers in its Oncology & Multispecialty and Medical-Surgical business units. Customers experienced intermittent service degradation, but McKesson said August 29 that they could use systems and services as intended while orders, distribution centers and shipping remained operational. ShinyHunters claimed responsibility and alleged a $55,236,150 data-extortion demand, but McKesson has not attributed the incident or confirmed ransomware deployment.

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