That is quite a leap to assume root access. A user mode database should have write access only to partitions that are mounted noexec. That would make getting

That is quite a leap to assume root access. A user mode database should have write access only to partitions that are mounted noexec. That would make getting root privileges quite hard even on a vulnerable kernel. Also with proper hardening you can prevent the kernel from being modified even by root. Things like FreeBSD securelevel that once enabled blocks writing to kernel memory and raw disk devices.