/usr/src/linux-headers-4.18.0-14-generic/Kconfig is in linux-headers-4.18.0-14-generic 4.18.0-14.15~18.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.18.0-14-generic/../linux-headers-4.18.0-14/Kconfig