Dry food that has become unpleasant or inedible due to improper storage (or because of its age) is described as stale.
stale food such as bread is old and no longer fresh
a package of stale crackers
get/go stale: Wrap the bread up well or it’ll get stale.
This is likely the closest answer to the question, however, it's not entirely fitting. Stale either means absorbed too much moisture or lost too much moisture.
You need to know how much moisture the food is supposed to contain in order to tell what stale means. For example:
If a potato chip has gone stale, it has absorbed enough moisture to change its texture and possibly its taste.
If a loaf of bread has gone stale, it has lost moisture, becoming dry and hard.
If a cookie has gone stale...we can't say. Some cookies are meant to be crisp and dry and some soft and moist. A Chips Ahoy! chocolate chip cookie is hard, so a stale Chips Ahoy! cookie has gotten moist. A Toll House chocolate chip cookie is typically soft, so a stale Toll House chocolate chip cookie has dried out.