Venmo did not immediately respond to WIRED’s request for comment. In a statement given to WIRED in response to questions about the Waltz and Wiles accounts, spokesperson Erin Mackey said, “We take our customers’ privacy seriously, which is why we let customers choose their privacy settings on Venmo for both their individual payments and friends lists—and we make it incredibly simple for customers to make these private if they choose to do so.”

“From my perspective, as a veteran, everyone is entitled to use the applications and services they feel are necessary to live their lives,” says Tara Lemieux, a 35-year veteran of the US intelligence community including the National Security Agency, Department of Homeland Security, and supporting agencies. “That said, when you post anything in those third-party applications and you don’t understand how that information can be shared or exploited, you are taking a risk for our nation—and that’s not acceptable.”

For Lemieux, while public transactions on Venmo might appear harmless, foreign intelligence services—particularly signals intelligence agencies—look for patterns: who’s paying whom, how often, and when. “Say they’re making payments to their children—now you have a point of leverage. If there’s someone out there looking to target you, they can use that information and start making you feel fearful for the safety of your children,” Lemieux says.

“The speed of the digital world has outpaced our ability to keep a handle on it,” she adds. “If you have all this information out there—how the heck are you going to put the toothpaste back in the tube?”

Mike Yeagley, a specialist in commercial data and its security risks, has spent over 15 years advising the US Department of Defense on how both allies and adversaries leverage what he calls “digital exhaust,” the seemingly mundane details—social connections, service transactions, and metadata trails—left behind in everyday apps. “At the highest level of our national security leadership, regardless of administration, there has to be an awareness of our data and what we project that can be discoverable,” he says.

“What’s the risk of someone at the Cabinet level using Venmo to pay their personal trainer? On the surface, it doesn’t look like much,” Yeagley says. “But now I know who that trainer is—or the gardener, or whoever—and suddenly I’ve expanded my ability to target by identifying the people around that official.”

Yeagley adds that “our adversaries are sophisticated and carnivorous in their data collection,” which means that “just the smallest bit of daylight is of interest to someone sophisticated. They will use that data point. They will build from it.”

According to Venmo, its “contact syncing” feature allows users to upload phone contacts to the app so that they can find people they know. When these exposed Venmo accounts were set up—all before 2020—the app would display a prompt allowing users to sync their phone contacts, automatically populating their friends list with anyone in their address book already using the platform. Venmo says this functionality was deprecated more than two years ago. Today, contact syncing no longer creates connections by default. To add someone as a friend, users have to search for them, send a request, and have it accepted.

Nevertheless, according to Venmo’s privacy policy, unless users proactively change their privacy settings, their network remains visible to anyone. That means that even when a user sets their account to private, their friends list remains visible unless they take an additional step. As of publication, hiding your connections requires navigating to Settings > Privacy > Friends List and selecting Private.

Stephen Lurie contributed reporting.