The obvious error in the first example is that they are sending credit card numbers over http, rather than using https.
> The obvious problem with this is that we’re given a reference to the product, and not the product itself.
Which isn't the most obvious problem with this example.
You might want to read: https://www.owasp.org/index.php/REST_Security_Cheat_Sheet
Deleted comment
> You missed the absence of Content-Length in some of my examples? If you're going to be on this internet, friend, you've got to step up your pedantry game.
https://github.com/teddziuba/teddziuba.github.com/commit/fd4...