CORS Policy Fix for REST API

My REST API hosted on a third-party service is being blocked by CORS policy. I need a fix ASAP to enable restricted access for specific clients.

Requirements:
- Expertise in CORS and REST APIs
- Experience with third-party API services
- Ability to implement secure access restrictions

Ideal Skills:
- Web security knowledge
- API configuration and management
- Problem-solving and quick implementation

Please provide a solution to bypass CORS restrictions and ensure secure, restricted access.