Am I considered disabled if I discover that I have cavus foot?

Usually having high arches is not associated with high levels of disability, unless in severe cases where mobility is greatly reduced as a result. With the correct shoes and arch support, the condition can be effectively managed and will limit the further progression or worsening of the condition. Disabled parking is normally reserved for people with severe disability or for people who are making use of assistive devices such as crutches or wheelchairs to aid in mobility.  Having said this, you can consult with a medical doctor regarding your condition and discuss this with them. If they deem your condition severe enough, they may grant you permit or disc to allow you to park in such spots.