What if box 3 social security wages has an amount but box 4 social security taxes withheld says zero?

A W-2C form is used to report a correction to your original W-2 form.

If you're sure you're getting a W-2C you should wait to file your return and disregard the original W-2.

Example use: A company that filed an incorrect amount on the employee's wages or withholding taxes uses this form to report the correct amount.