This is a fine article, but of course, you should never use RSA implemented like this. In fact, the PKCS1v15 implementation here is itself vulnerable to a textbook padding oracle attack (it errors out on busted padding). This is in set #6 of the cryptopals challenges and is a pretty fun way to learn some things about how RSA works.
A cool recent paper on automating not just this attack but all kinds of "format oracle" attacks --- padding, headers, &c --- using SMT solvers:
A cool recent paper on automating not just this attack but all kinds of "format oracle" attacks --- padding, headers, &c --- using SMT solvers:
https://eprint.iacr.org/2019/958.pdf