Trello Data Breach: Hacker Dumps Personal Info of Millions of Users

**Executive summary:** A threat actor leaked 21.1 GB of Trello data (published July 16, 2024) that the actor says was obtained in January 2024 by abusing an unauthenticated API endpoint to map email addresses to Trello accounts; the dump reportedly contains ~15.18 million email addresses and other personally identifiable information, creating significant risk of doxing and phishing and highlighting weaknesses in API authentication and posture management.