MySQL - The DBMS must maintain a separate execution domain for each executing process
I guess the answer depends on how you define the term "process".

MySQL is a single-process DBMS; each connection runs as a separate thread, but they share the same process address space. Subsequently, there's nothing that prevents one thread from accessing another thread stack, for example. 

In the spirit of the rule text you quote MySQL is "not capable of maintaining a separate execution domain for each executing process" -- if by "process" you understand a client connection.

However, if you stick to the letter of the rule, since there's only one DBMS process at the OS level, no isolation is necessary apart from the process isolation provided by the underlying operating system.