WASHINGTON, D.C. — The Department of Homeland Security (DHS) is investigating a breach of its Homeland Security Information Network (HSIN) after hackers reportedly accessed HSIN servers during late May and early June 2026. Nextgov and Bleeping Computer reported that DHS officials are probing the cyberattack. A DHS spokesperson stated the department is "aware of a recent cyber incident involving a specific, unclassified legacy information sharing environment." The spokesperson added that the department "immediately took action to isolate the affected systems, mitigate the vulnerability, and launch a comprehensive forensic investigation." The investigation into the cyber incident is ongoing.

The Homeland Security Information Network serves as a platform for federal, state, and local governments, as well as law enforcement, to share intelligence. Though the intelligence shared over HSIN is unclassified, Mark Warner, a Democratic senator representing Virginia and ranking member of the Senate Intelligence Committee, stated that the exposure of HSIN information "is highly sensitive, and its exposure risks national security." It is currently unclear what data was stolen or the volume of data taken during the HSIN breach, and the identity, affiliation, and motives of the hackers who targeted HSIN are not yet known. A 2023 security lapse revealed that HSIN contained personal information related to the surveillance of Americans shared among law enforcement.

Senator Warner noted that the HSIN platform is currently supporting the World Cup games in the United States. He also stated that HSIN was used in 2025 to manage the response to a mid-air collision over Washington, D.C., involving an American Airlines jetliner and a U.S. Army Black Hawk helicopter. That incident killed 67 people. The Trump administration took office in January 2025.