Broken authentication poses significant security risks, likened to leaving gates open for bandits, and emphasizes the importance of protecting APIs, reinforcing authentication, and securing API keys. Weak authentication methods can lead to unauthorized access, allowing attackers to exploit weak passwords, brute force, and credential stuffing. Including sensitive information in URLs or using weakly signed JWTs can expose systems to unauthorized access, making it crucial to validate access tokens and ensure JWTs are properly signed. Following these practices helps safeguard sensitive data, maintain customer trust, and protect organizational resources from malicious actors.