DHS Investigates Cyber Breach in Homeland Security Information-Sharing Network

The U.S. Department of Homeland Security (DHS) has launched an investigation into a cybersecurity breach involving an unnamed government information-sharing network, raising fresh concerns about the security of sensitive federal systems.

In a statement released Thursday, DHS confirmed it was examining a "recent cyber incident" affecting what it described as an "unclassified legacy information sharing environment." The agency did not identify the network involved or disclose additional details about the scope of the breach. DHS also declined to answer follow-up questions regarding the incident.

According to a report by GovExec, citing two people familiar with the matter, the compromised platform is believed to be the Homeland Security Information Network (HSIN). The network is widely used by federal agencies, state and local governments, foreign law enforcement partners, and other authorized organizations to exchange sensitive but unclassified information related to public safety, emergency response, and homeland security operations.

The report said the cyber breach likely occurred between late May and early June, although officials have not publicly confirmed the exact timeline or whether any information was accessed or stolen during the incident.

The disclosure has prompted concern among lawmakers over the potential national security implications. Senator Mark Warner of Virginia, the ranking Democrat on the Senate Intelligence Committee, warned that while the information stored on the network is not classified, it remains highly sensitive and could pose significant security risks if exposed.

Warner urged both the Department of Homeland Security and the U.S. Department of Justice to conduct a comprehensive investigation into the cyberattack. He called for authorities to determine who was responsible, how the breach occurred, and what data, if any, was compromised.

The DHS cyber investigation comes as federal agencies continue to strengthen cybersecurity defenses against increasingly sophisticated attacks targeting government networks and critical infrastructure. The outcome of the investigation is expected to provide greater clarity on the extent of the breach and whether additional security measures will be required to protect sensitive information-sharing systems in the future.