TeleMessage, a company that makes a modified version of Signal that archives messages for government agencies, was hacked.

A hacker has breached and stolen customer data from TeleMessage, an obscure Israeli company that sells modified versions of Signal and other messaging apps to the U.S. government to archive messages, 404 Media has learned. The data stolen by the hacker contains the contents of some direct messages and group chats sent using its Signal clone, as well as modified versions of WhatsApp, Telegram, and WeChat. TeleMessage was recently the center of a wave of media coverage after Mike Waltz accidentally revealed he used the tool in a cabinet meeting with President Trump.

The hack shows that an app gathering messages of the highest ranking officials in the government—Waltz’s chats on the app include recipients that appear to be Marco Rubio, Tulsi Gabbard, and JD Vance—contained serious vulnerabilities that allowed a hacker to trivially access the archived chats of some people who used the same tool. The hacker has not obtained the messages of cabinet members, Waltz, and people he spoke to, but the hack shows that the archived chat logs are not end-to-end encrypted between the modified version of the messaging app and the ultimate archive destination controlled by the TeleMessage customer.