Assuming you're a black hat exploiting this bug, what can you do, if the target is using a VPN?
I don't know what "address of the credit cards" means, but let's assume it's the target's home address.
You don't get their credit card number or security code. You don't get access information on any of their web accounts. Correct?
If you spy on their internet activity during the flight, it's all encrypted. You won't learn anything.
However, you do have the ability to change their password, so they can't get into their own account anymore.
You could also bill all your own activity to their account. I don't know if you can bill other things to the account.
You could get access to whatever data was stored in that account. I don't know what that would be, other than when & how much you used it in the past.
Is this a complete summary of the potential damage?
Since there's no Reply button for the two answers to this:
Neither of them answer my last question ("is this a complete summary..."). Should I assume it is?
And I never said "oh but the data leak isn't really that bad of a vulnerability" -- you did.
This has to do with API endpoints that exposed customer information and allowed password changes without checking that the request was coming from the customer. The customer didn't have to be logged in to the account, or even on the flight in the first place. If they had an account, it was exposed.
Maybe you could just admit that and end the argument. This doesn't require you to minimize the seriousness of the bug.
I tried to summarize what the vulnerability is. Why are you so upset about that?
Going by the same logic, what can a black hat exploiting this bug do if the target ISN'T using a VPN?
Using or not using a VPN in the context of this bug is totally irrelevant.
OP said "what would not being on VPN let someone do to you?"
not
"what harm could occur if you're not in the air?" or
"does using a VPN protect you from all harm?"
and the question/assertion is, "if you were in the air, and not on VPN, then could a black hat who's compromised your account spy on your traffic?"
And even if they could, any sensitive page should be using HTTPS, so the data will be encrypted. A VPN still wouldn't make a difference.