Flask is a powerful, lightweight, and versatile web framework for Python that's designed to make it easy for developers to develop web applications quickly with minimal boilerplate code. However, just like any other web framework, Flask is susceptible to vulnerabilities if it's not properly secured. The most common security risks for Flask include cross-site scripting (XSS), cross-site request forgery (CSRF), and SQL injection. To mitigate these issues, developers can follow best practices such as disabling the debug mode in production, using environment variables to store sensitive information, and implementing proper error handling and logging mechanisms. Additionally, using libraries like Flask-WTF for CSRF protection and Snyk for vulnerability scanning can help ensure the security of Flask applications. By following these best practices, developers can build secure and reliable web applications with Flask.