DHS Probes HSIN Information-Sharing Breach

The U.

S. Department of Homeland Security is investigating a cyberattack against the Homeland Security Information Network, a sensitive information-sharing platform used by government and private-sector partners. The intrusion likely occurred between late May and early June 2026 and affected unclassified, legacy information in HSIN and an associated collaboration environment; DHS isolated affected systems and said there was no indication that classified networks were impacted. The incident matters because HSIN supports interagency coordination, including security planning and communications related to major events such as the World Cup.