A new analysis of TM Signal’s source code appears to show that the app sends users’ message logs in plaintext. At least one top Trump administration official used the app.

TeleMessage lets users archive their chats in secure messaging apps. However, the hacker reportedly found that TeleMessage’s archived chat logs aren’t end-to-end encrypted, allowing them to access the contents of certain messages, government official contact information, and login credentials for the service’s backend.

A hacker reportedly stole customer data from a company that makes a Signal-like app that former National Security Adviser Mike Waltz was seen using in a Cabinet meeting with President Donald Trump.