Frankly nothing. At least technically nothing. A web shop owner can jolly well sell your credit card data on the dark web or wherever. People can buy it from there and use it to make purchases on your credit card. Of course, you’d have fraud protection from your credit card issuer bank and likely be able to recover your money in full, but that doesn’t prevent the misuse from happening in the first place.
This won’t work in India, where credit card payments are subject to two factor authentication and the web shop owner could not have stolen all the info required to pass 2FA. But it will work in countries that don’t have a 2FA regime, and that’s a vast http://www.montauk-monster.com/cialis-generic majority of the world.
Now, business wise, there are safeguards against web shop owners misusing credit card data such as loss of trust, loss of reputation, etc. These can preclude outright misuse. But these safeguards are only as strong as the pedigree of the web shop owner.
That’s why many people prefer to shop only at a few reputed web shops, rather than all over the place and leaving their credit card data everywhere. Over a period of time, this causes an attrition in web shops. Along with preferential VC funding, this is one of the major drivers of the so-called “Winner Takes All” tendency in Consumer Internet.