DHS investigates breach of information sharing platform

The Department of Homeland Security (DHS) is investigating a cyberattack on its Homeland Security Information Network (HSIN), an unclassified platform used by federal, state, and local governments and law enforcement to share intelligence and coordinate emergency responses. According to news site Nextgov, hackers reportedly broke into HSIN servers during late May and early June. The incident, which constitutes a breach of its platform, potentially exposed information shared using the system. While the platform is unclassified, it is used by various agencies to plan, coordinate, and share information about major events and respond to emergencies.

An unnamed DHS spokesperson confirmed that the department is aware of a recent cyber incident involving a specific, unclassified legacy information sharing environment. The spokesperson added that they immediately took action to isolate the affected systems, mitigate the vulnerability, and launch a comprehensive forensic investigation. The spokesperson declined to comment further on the ongoing investigation. However, the exposure of this data has drawn sharp criticism from lawmakers. Mark Warner, a Democratic senator representing Virginia who also serves as the ranking member of the Senate Intelligence Committee, warned in a statement that the information “is highly sensitive, and its exposure risks national security.” Warner noted that the HSIN platform was used to manage the response to a mid-air collision of an American Airlines jetliner and a U.S. Army Black Hawk helicopter over Washington, D.C., which killed 67 people.

The cyberattack puts fresh scrutiny on the government’s ability to defend the cybersecurity of its own systems. This incident follows a previously reported security lapse during 2023, which revealed that HSIN contained personal information shared among law enforcement. It also adds to a series of major cybersecurity breaches across the federal government since the Trump administration took office in January 2025. These incidents include the raiding of federal databases of Americans’ personal information by members of the Department of Government Efficiency (DOGE), a public spill of credentials by a contractor for the Cybersecurity and Infrastructure Security Agency (CISA) that exposed access to government cloud systems, and a major cyber incident that the FBI notified Congress of after exposing surveillance targets’ phone numbers.

Why it matters

The breach of the Homeland Security Information Network (HSIN) raises concerns about national security and the federal government’s cybersecurity posture following a series of recent incidents.