The Possession action, typically found on Ghosts, includes the following description of the effects of successfully possessing a creature:
The ghost now controls the body but doesn't deprive the target of awareness. The ghost can't be targeted by any attack, spell, or other effect, except ones that turn undead, and it retains its alignment, Intelligence, Wisdom, Charisma, and immunity to being charmed and frightened. It otherwise uses the possessed target's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies.
It is unclear to me if feats count as a thing that the ghost doesn't gain access to (i.e. "knowledge, class features, or proficiencies"). Does a ghost that successfully uses Possession on a character gain access to the character's feats?