/usr/lib/x86_64-linux-gnu/libcfg.so.6 is in libcfg6 2.4.2-3+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libcfg.so.6.0.0
/usr/lib/x86_64-linux-gnu/libcfg.so.6.0.0