thats something that should be fixed, how can you claim to be neutral while allowing one side to use all of their armed forces offensively from your territory?
Franco did allow the Kriegsmarine to resupply submarines - and to a lesser extent, the Luftwaffe to resupply planes - on Spanish territory many times during the war. Though each was a covert act, authorized specifically, rather than a blanket "military access" deal; captured documents hint as as much as 60 instances of the event between 1940 and 1943. After the Axis lost Lybia, though, Spain refused further requests.
The UK was aware, but did not pursue the issue; at least not publicly.
A lesser-known facet of the war, yes, but these details of history show that some things we believe impossible did in fact happen.