Permission sets can address CRUD/FLS security requirements by configuring access to objects and fields. They enforce create, read, update, and delete permissions (CRUD) as well as field-level security (FLS) settings. However, developers must ensure these settings are properly implemented in the code. To validate access programmatically: use `WITH USER_MODE` for SOQL queries and `AccessLevel.USER_MODE` for Database methods to automatically enforce permissions, or use methods like `isAccessible()`, `isUpdateable()`, and `isCreateable()`, and utilize tools like the `stripInaccessible` method to filter out fields or objects that a user cannot access. Proper implementation and validation are essential to ensure compliance with security requirements.