> Harvard - 850,537 breached accounts

In November 2025, Harvard University suffered a data breach later linked to a ShinyHunters "pay or leak" extortion attempt. The data contained 851k unique email addresses relating to the university's alumni and fundraising systems, along with extensive profile information for donors, alumni, parents and some faculty, staff and students. In Harvard's disclosure notice, the university stated that the breach impacted "personal information such as email addresses, telephone numbers, home and business addresses, event attendance, details of donations to the University, and other biographical information pertaining to University fundraising and alumni engagement activities".