I regularly use my credit card on-line, and on a lot of sites I must give them the 3 digit code to finish processing the transaction. As yet, I have not had a problem (knock on wood).
Just make sure you are on a website that you trust, and you can see the security encryption icon for the site. It’s usually at the top of your web browser and looks like a padlock. Move your cursor over it and it should indicate that the site is secure. If you don’t have that, then it may be a phisher site trying to steal your credit card info.

Giving personal info such as credit card numbers or social security number is always risky on line. If you are positive that you are giving the numbers to a legitimate company through a trusted encrypted site then it should be safe however if there are any doubts whatsoever about the company or the website and whether its a safe encrypted site then I would hesitate to give those numbers. Be VERY cautious. There are lots of hackers on line just trying to steal your ID and personal bank account numbers etc and its called phishing.
yep , just dont give it to people askin for it if ur not buyin anything,