Water damage in cupboard - nasty mess!

[diydisasters100]

I've just discovered this in my aunt's kitchen cupboard (cupboard under the sink). I'm going to clean the cupboard out and see if I can see where the leak/water has come from but I'm just wondering if there's an easy way to fix it?

I'm not a DIY'er naturally but always willing to have a go! I'm assuming if I tear the strip off I might be able to sand down the damaged area? Any idea what the strip is called so I can buy a replacement?

The water is probably all through the board which means it is not an easy fix. I'd either leave it to dry and then ignore it or replace the whole cupboard

I've had a quick look and the inside of the cupboard looks really solid and undamaged.

I think it might she might have let water dribble down the cupboard door while draining dishes so hoping it is just superficial damage.

Can you remove the kickboard under cupboard? A screwdriver might help. If there's a leak it'll be evident on floor, but could just be years of damp water splashing down over the years.

Either way, leave door open and allow to drive out. After a bit of clearing, she'll probably just live with it.