At least three of America’s largest data brokers are potentially harming national security by selling information on U.S. active-duty military personnel, according to new research from Duke University. Data brokers are companies that buy and sell online information in bulk—facilitating legitimate business such as credit scoring, advertising, and research. However, critics say the industry is ripe for abuse. Privacy advocates have raised concerns that data brokers enable government to bypass Fourth Amendment protections by purchasing data instead of obtaining a warrant, while civil libertarians have compared the industry’s “consumer scores” to China’s social credit system. On Monday, Duke University’s Data Broker Project released a report finding that three major data brokers—LexisNexis, Acxiom, and Nielsen—are selling information on U.S. active-duty military members. “LexisNexis advertises a capability to search an individual and identify whether they are active-duty military,” the Duke report said. “Acxiom also offers ‘verification and location of military servicemen (deployed …