A hacker was able to easily gain access to a website. He was able to log in via the frontend user login form of the website using default or commonly used credentials. This exploitation is an…

Insufficient security management refers to failures at the organizational or governance level - such as lacking security policies or oversight programs - not a specific technical misconfiguration like default credentials.

Insufficient database hardening means the database or application was not properly secured before going into production, including leaving default usernames and passwords unchanged. Security hardening practices require removing, disabling, or changing all default accounts and credentials. Leaving these in place allows attackers to trivially authenticate using publicly known defaults.

Insufficient input validation refers to failing to sanitize or reject malicious user-supplied data (such as in SQL injection or XSS scenarios), which is unrelated to credential management or authentication defaults.

Insufficient exception handling refers to not properly catching or managing runtime errors in code, which is a software reliability and information disclosure concern, not an authentication configuration flaw.