For Galileo they have something where basically each message contain something to authenticate the previous one. So this could be fully based on ground segment. Anyway, they have probably countless reasons to update software anyway considering the many services that were added after their launches years ago.
What GNSS satellites do is (approximately) timestamp a message they receive from ground. They don’t really know their position by themselves, they are clocks in orbit.
Je ne sais pas si les agences de l’ONU et celles de l’Union Européenne ont un statut special comparé aux autres (ESA, OTAN, EPO, etc.) mais j’imagine que le même genre de problèmes existent là bas aussi. De ce que j’ai compris dans la plupart de ces organisation tu as plus de mobilité, ça peut expliquer les moindres incidents