Oracle RDBMS version 12.1 and above versions use a new security measure for the UTL_* packages.
A new security measure is introduced in this release for the following network-related PL/SQL packages: UTL_TCP, UTL_HTTP, UTL_SMTP, UTL_MAIL, and UTL_INADDR. The invoker of those packages needs additional privileges to connect to an external host or to resolve the name or the IP address of a host. The network packages check the invoker for the necessary privileges at runtime. It raises an exception if the invoker lacks the privileges. The exception is Oracle error
ORA-24247: network access denied by access control list (ACL).
These packages do not allow connections to external network services to non-privileged users by default.