Just checked the brakes before putting the car into a few months of storage and only the outer 2 of the 4 brakelights lit up, and wanted to ask if that could be a wire/grounding issue or just blown bulbs, wanted to know if it could be a possible hazard that requires immediate attention
It's a 91 vert and all the normal rear lights work if that's relevant

 

As long as they're lighting up properly when the brake is depressed (don't forget the high brake light above the license plate) then imo it's fine for now. But for safety reasons they should all be working as soon as you can. You can also be pulled over for having non-functional lights.

Swap the bulbs from the working sockets to the non-working and see what happens. If they work then you just need new bulbs.

 

they share a ground

 

Thanks!