Explore information disclosure vulnerabilities in APIs and HTML page sources often overlooked by researchers in mature programs. Learn about the design pattern in Rails that makes these vulnerabilities easy to introduce, especially when combined with front-end JavaScript libraries like React or Angular. Discover how to identify and exploit these vulnerabilities through real-world examples, including customer ID exposure and private address leaks. Gain insights into why these issues occur and how to prevent them in your own applications. Perfect for security researchers, developers, and anyone interested in improving API security.