DHS Investigates Breach of HSIN Information-Sharing Network

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DHS Investigates Breach of HSIN Information-Sharing Network

First seen 1 Jul 2026, 18:04 UTC • •51.9

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ThreatCluster •July 2, 2026 at 14:06 UTC

•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.

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.

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Timeline

2026-05-01

Breach of HSIN detected

An unknown threat actor accessed the HSIN network, compromising sensitive data shared among partners.

2026-06-30

Nextgov reports HSIN breach

Nextgov reported on the breach, highlighting potential exposure of sensitive data during World Cup security preparations.

2026-07-01

DHS confirms HSIN breach

DHS confirmed the breach and stated that classified systems were not impacted, while investigations continue.

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More articles in this cluster (23)

Threat Graph

6 entities, 5 inferred relationships (STIX 2.1).

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Technique (1)

Data Breach

Organization (1)

Department of Homeland Security

Weakness (1)

CWE-200 - Exposure of Sensitive Information

Affected Platform (3)

Homeland Security Information Network
HSIN
SharePoint

Relationships

Data Breach targets Homeland Security Information Network
Data Breach targets HSIN
Data Breach targets SharePoint
Data Breach related to Department of Homeland Security
Data Breach related to CWE-200 - Exposure of Sensitive Information

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