Localhost dangers: CORS and DNS rebinding - The GitHub Blog

Cross-Origin Resource Sharing (CORS) allows websites to communicate with each other, but improperly configured CORS policies can lead to vulnerabilities. Developers often use broad or faulty CORS rules, allowing attackers to bypass authentication and execute remote code. Real-world examples demonstrate how these misconfigurations can result in significant security risks, including remote code execution and unauthorized access to sensitive data.