A breach of the Pentagon’s human resources system exposed Social Security numbers and other personal information belonging to current and former military personnel, according to a letter sent to affected people by the Defense Manpower Data Center (DMDC). The incident has raised counterintelligence concerns among national security experts.
The DMDC said “unauthorized users” accessed a vulnerable computer server from October 2025. The Pentagon did not discover and remediate the problem until July 2026, meaning the unauthorised access lasted about nine months. The details were reported after CNN reviewed the DMDC’s letter to victims. The centre’s website said it held at least 60 million records as of fiscal 2024, although the supplied report does not specify how many records were accessed or identify the affected individuals in more detail.