I suspect my passport information along with other personal information was leaked on a website. I have already setup Credit Freeze, would Fraud Alert be also necessary? What are the benefits and drawbacks of using a Fraud Alert over a Credit Freeze?
Effectively, a Fraud Alert is weaker than a Credit Freeze. if you already have a Freeze, you don't really need an Alert.
A Credit Freeze stops a bureau from giving anyone your credit report, even if the requester claims they have your authorization. It stops people from opening new accounts in your name, or even getting your credit report at all. A Freeze can be reversed by using a verified account with the bureau and/or supplying a unique PIN that was chosen when the freeze was put in place.
A Fraud Alert still allows credit reports to be pulled, but it requires a manual verification first. Typically, if you have a Fraud Alert, the bureau will present challenge questions based on the contents of your credit report, in order to allow the requester to verify if you are really you. For instance, they may ask something like, "what was your mortgage payment on the home you owned 10 years ago?" As an example of how the process works, if you are at a bank trying to get a mortgage, and the lender tries to pull your report, they would get presented with the challenge questions instead of receiving your report. You then simply provide the answers to the lender, and the lender submits them to the bureau, and the bureau releases your credit report.
Meanwhile, if you went to a bank and tried to get a mortgage while you had a Freeze, the lender would basically tell you that you're out of luck, and you need to contact the bureau directly, remove the freeze, and then get back to them.
The problem with an Alert is that it's easy to defeat if someone has all of your information. I've watched pen testers defeat freezes based on information they guessed after some careful web searches about their target (for instance, looking up their home address in public tax records, finding the sale price they paid for their home, plugging it into a mortgage calculator, and then guessing what their monthly payment is).
If you are especially nervous, you should contact the three major bureaus directly, explain your exact situation, and verify with them how their systems will work.
You should read the State Department's guidance on cases where your passport information is obtained.
Basically, they say don't worry about it. Your passport number, plus $6, will get the fraudster a small coffee at Starbucks, but not in the sterile area of an airport! The fraudster can't do anything with that number, because anything you'd do with a passport number also requires the passport to be physically present. And passports are so hard to counterfeit that state actors have trouble doing it, which is kind of the point.