What are the security implications of relying solely on `X-Forwarded-For` to get the original IP address?

The `X-Forwarded-For` header is easily spoofed by malicious users. They can add or modify the header to appear as if they are coming from a different IP address. Therefore, relying solely on this header for security measures like rate limiting or blocking can be dangerous and ineffective. Always prioritize `CF-Connecting-IP` when available.