WASHINGTON, D.C. — The Department of Homeland Security is investigating a breach of its Homeland Security Information Network (HSIN), according to reports from Nextgov and Bleeping Computer. Hackers reportedly accessed HSIN servers during late May and early June 2026, potentially exposing information shared using the platform.

A DHS spokesperson stated, "We are aware of a recent cyber incident involving a specific, unclassified legacy information sharing environment." The spokesperson added, "We immediately took action to isolate the affected systems, mitigate the vulnerability, and launch a comprehensive forensic investigation."

HSIN is a platform utilized by federal, state, and local governments and law enforcement agencies for intelligence sharing. U.S. Senator Mark Warner, a Democrat representing Virginia and ranking member of the Senate Intelligence Committee, commented on the situation. "The information is highly sensitive, and its exposure risks national security," Warner said.

The extent of data stolen and the specific contents remain unclear. This incident follows a 2023 security lapse where HSIN was found to contain personal information related to surveillance of Americans shared among law enforcement. HSIN is currently supporting the World Cup games underway in the United States.

In 2025, HSIN was used to manage the response to a mid-air collision involving an American Airlines jetliner and a U.S. Army Black Hawk helicopter over Washington, D.C. Earlier in 2026, the FBI notified lawmakers in Congress about declaring a "major cyber incident" after exposing phone numbers of targets under federal surveillance. This incident also fits a pattern of recent security and exposure concerns within federal agencies, including the FBI's notification to Congress earlier in 2026 about a "major cyber incident." The historical use of HSIN in responding to major incidents, such as the 2025 mid-air collision, demonstrates its importance in critical situations.