Massive Columbia University data breach affects nearly 900,000 past and present students - here's what was leaked, and how to stay safe

• Columbia University files form with the Maine Attorney General's Office
• It confirmed the number of victims, and the type of data stolen
• Victims are being offered free credit and identity theft monitoring services

A massive cyberincident affecting almost 870,000 Columbia University students, employees, and other individuals occured in May 2025, the university has confirmed.

In a new filing with the Office of the Maine Attorney General, the university said in late June 2025 it experienced an outage in its IT systems, prompting an investigation with the support of third-party cybersecurity and forensics experts.

The investigation confirmed the outage was the result of a cyberattack, in which yet unidentified perpetrators stole sensitive data on exactly 868,969 people, including employees, applicants, students (both current and former), and various family members.