Deputies of Elon Musk have sought access to massive amounts of information across the federal government, much of it personal and highly revelatory in its insights into the lives of everyday Americans. They justify their work for the U.S. DOGE Service as a dogged quest for government efficiency. But people with deep knowledge of federal data systems and cybersecurity say they’re skirting guardrails meant to protect sensitive data from misuse. Before DOGE launched, most of the records at issue were kept in the hands of a select few officials to preserve privacy and avoid crossing legal red lines. Now Musk’s...