DHS Investigates Breach of HSIN Information-Sharing Network

The Department of Homeland Security (DHS) is investigating a breach of the Homeland Security Information Network (HSIN), which occurred between late May and early June 2026. An unknown threat actor accessed the network, potentially exposing sensitive data shared among federal, state, local, and private-sector partners. The attack targeted HSIN servers and a SharePoint system used for collaboration. DHS has not attributed the attack to any specific group and is assessing the extent of the damage. The breach raises concerns about the security of information related to major events, particularly with the World Cup taking place across the U.S. The system remains operational for partners, and classified networks were not affected. This incident follows a previous security issue in 2023 involving an access misconfiguration that exposed sensitive data. The investigation is ongoing, and DHS has taken steps to isolate affected systems.

Key Points: • DHS is investigating a breach of the HSIN information-sharing network. • The intrusion occurred between late May and early June 2026, affecting sensitive data. • No specific threat actor has been identified, and classified systems remain unaffected.