The RSA cryptosystem has had its fair share of attacks over the years, but among the most impressive, you can find the infamous Bleichenbacher attack [Ble98], which doomed PKCS v1.5 in 1998. Nineteen years later, the ROBOT attack proved that the Bleichenbacher attack was still a concern today. Now, what alternatives to RSA PKCS v1.5 do we have?
Well, itssuccessor, RSA OAEP also known as RSA PKCS v2.1 is obviously a good candidate.
Source: kudelskisecurity.com