FBI labels data breach ‘major incident,’ notifies Congress

The FBI has labeled a recent data breach, which reportedly targeted an FBI surveillance system, a “major incident” and notified Congress about the cyber intrusion, the agency confirmed to The Hill on Friday.

“The FBI identified anomalous activity on an unclassified network and quickly leveraged all technical capabilities to remediate the incident,” the agency said in a statement. “It was determined the access was obtained through a third party and constitutes a major incident under the Federal Information Security Modernization Act (FISMA).”

“The FBI is following the required steps under FISMA, including notifying Congress, and remains focused on countering nation-state and cybercriminal activity,” it continued.

Several outlets reported that China-linked hackers are suspected of being behind the breach.

According to Politico, the system contained information from pen register and trap and trace devices, which are used to monitor incoming and outgoing calls from a phone, as well as personally identifiable information related to subjects of FBI investigations.

The government has defined a “major incident” under FISMA as “any incident that is likely to result in demonstrable harm to the national security interests, foreign relations, or economy of the United States,” according to 2025 guidance. It can also constitute an incident involving personally identifiable information that presents similar risks.