Originally Posted by clifford79

In ZRH, the priority security lane is for all *G when going from landside to airside.

When flying FLR-ZRH-GRU you won't pass through any security in ZRH unless you go landside (e.g., take the train to downtown Zürich during your layover), and in this case you can use the priority security lane.

For the return, it might be different if there is some additional transfer security when you connect GRU-ZRH-FLR (if GRU is considered "unsafe"), but in general you don't need to pass through any security checks anymore when transferring in ZRH.