Keen Smell. The Zombie Cat has advantage on Wisdom (Perception) checks that rely on smell.

Undead Fortitude. If damage reduces the Zombie Cat to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the Zombie Cat drops to 1 hit point instead.

Stench. Upon dying any creature that's within 5 ft. of the Zombie Cat must succeed in a DC 8 Constitution saving throw or take 2 (1d4) poison damage, taking no damage on a successful saving throw.

Claws. Melee Weapon Attack: +1 to hit, reach 5 ft., one target. Hit: 2 (1d4) slashing damage.