Pete Hegseth, Mike Waltz, Tulsi Gabbard: Private Data and Passwords of Senior U.S. Security Officials Found Online
www.spiegel.de
Donald Trump's most important security advisers used Signal to discuss an imminent military strike. Now, reporting by DER SPIEGEL has found that the contact data of some of those officials, including mobile phone numbers, is freely accessible on the internet.

TL;DR:

Reporters at Der Spiegel claim to have found phone numbers, email addresses, and social media login credentials for multiple top White House officials, including National Security Adviser Mike Waltz, Director of National Intelligence Tulsi Gabbard, and Secretary of Defense Pete Hegseth.

They also claim to have “revealed an additional grave, previously unknown security breach at the highest levels in Washington.” Though the article does not divulge details.

Edit: Reading comprehension failure on my part.