/usr/src/linux-headers-4.10.0-42-generic/security is in linux-headers-4.10.0-42-generic 4.10.0-42.46~16.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.10.0-42-generic/../linux-headers-4.10.0-42/security