Place dried navy beans into a large container and cover with several inches of cool water; let soak, 8 hours to overnight. Drain.
Heat 2 to 3 tablespoons of water in a pot over medium-high heat. Add onion and cook until translucent, about 5 minutes. Add garlic and more water if necessary; saute for 2 minutes. Add vegetable broth, pre-soaked beans, curry powder, lemon balm, white pepper, and cayenne; bring to a boil.
Reduce heat to medium-low and simmer until beans are nearly tender, about 1 hour. Add squash to the simmering beans and bring back to a very slow boil. Simmer until squash and beans are tender, about 30 minutes more. Allow to cool slightly; use an immersion blender or transfer to a blender to blend until soup is smooth and creamy.
Add corn to the pot and adjust seasoning as necessary. Heat to a slow boil and then reduce to a simmer. Continue to simmer until corn is tender, about 10 minutes.