The Department of Homeland Security is investigating a breach of its Homeland Security Information Network (HSIN), a platform used by federal, state, and local governments and law enforcement to share intelligence and coordinate responses to major events and emergencies.
Hackers reportedly broke into HSIN servers during late May and early June 2026. A DHS spokesperson confirmed the department is “aware of a recent cyber incident involving a specific, unclassified legacy information sharing environment,” adding that officials “immediately took action to isolate the affected systems, mitigate the vulnerability, and launch a comprehensive forensic investigation.” The investigation remains ongoing.
It is unclear what data was stolen or how much was taken. The identity, affiliation, and motives of the attackers have not been disclosed.
Senator Mark Warner, a Virginia Democrat and ranking member of the Senate Intelligence Committee, warned that while the intelligence shared over HSIN is unclassified, the information “is highly sensitive, and its exposure risks national security.” Warner noted that HSIN is currently supporting the World Cup games underway in the United States and was also used to coordinate the response to the 2025 mid-air collision between an American Airlines jetliner and a U.S. Army Black Hawk helicopter over Washington, D.C., which killed 67 people.
The breach adds to a series of cybersecurity incidents affecting the federal government since January 2025. These include the sharing of classified war plans over uncleared apps like Signal, access to federal databases by members of DOGE, a public spill of passwords and credentials by a CISA contractor, and an FBI incident involving exposed phone numbers of surveillance targets that required the agency to declare a “major cyber incident.”
The HSIN attack comes amid significant budget cuts to federal cybersecurity operations, including at DHS and its cybersecurity agency CISA, under the Trump administration. A previously reported 2023 security lapse had already revealed that HSIN contained personal information related to the surveillance of Americans.
Source: TechCrunch