The leather details and seats of your vehicle give it a premium look but can easily be ruined by a spot of paint. If you don't get to it quick enough the paint can spread and leave behind a permanent stain on your leather. To remove this type of stain you will need to use something a little more heavy duty than your standard cleaning products but with proper care and testing the cleaner on a small area of the seat it shouldn't be too difficult.
First off if the paint is still wet or hasn't been on the leather too long it may be possible to just wipe away the paint with a cloth soaked in clean warm water. This will be the case with most water-based paints but acrylic and wall paints that have had time to dry might require a little more scrubbing.
If the paint is a bit more dried up it might be necessary to use a mild solvent like turpentine or a similar product that is safe for your vehicle's leather. When using such a chemical it is best to work in an area with plenty of ventilation to avoid inhaling fumes and to prevent any physical damage to the leather itself. It is also a good idea to always test your cleaner on an inconspicuous area of the seat before going ahead and applying any chemicals that could potentially cause harm.
If you have tried a variety of methods and the paint is still present you can try using a petroleum jelly such as Vaseline. This will moisten and loosen the paint stains and can then be peeled off of the upholstery. It is also a good idea to condition the leather afterward to help restore its suppleness.