This is a too-common issue, as Nissan neglected to provide a good watertight cap for those strut bolt ends. Usually all that is needed is a good cleanup, maybe a new nut, some grease and an improvised or aftermarket plastic or rubber cap. In at least one of these, though, it's possible a new or used strut might be needed, just to get a good threaded top mounting rod. I wouldn't pass on a car based on this, but look for serious rust elsewhere, and price a strut; you might get that much knocked off the price.
Brilliant Silver 2021 Leaf SV40 W/ Pro Pilot & Protection
2009 Vectrix VX-1 W/18 Leaf modules, & 2 lithium E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.