The first and least risky/work intense step is to use baking soda. Rub it into the lining of the jacket or put the jacket insides out in a bag with baking soda and shake and leave like that for a day. The natron in baking soda neutralizes most smells and you can get off remaining baking soda very easily. Step two is putting the jacket into the freezer/outside in cold winter night. Cold kills most bacteria responsible for the smell. That's why Levis recommends putting their jeans into freezer rather than washing them too often. Works for wool lining in jacket too. Did it before, the cold did no harm to the leather that I could see. If jacket still smells after this, tape zipper so it doesn't get damaged and put the jacket into the washer at 30° with some neutral washing elixir that doesn't damage the leather. Don't put jacket into tumbler afterwards (too warm) , leave it hanging for two days or so until it's dried. You probably have to treat leather after this.