In summary, Ada tries to be memory safe by default -- as far as that can be done without requiring automatic memory management and garbage collection -- but deliberate use of "unchecked" language features can break memory safety.
In other words, if you go out of your way to use unsafe features, and don't use the features that compensate, Ada is memory unsafe. This has become the goto dismissal of Ada, apparently more popular than "eww...a BEGIN..END language" and "designed by committee/government tainted".
http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-13-9-1....
https://old.reddit.com/r/ada/comments/mme3jk/is_ada_memory_s...