/usr/lib/x86_64-linux-gnu/libnm-util.so is in libnm-util-dev 0.9.10.0-7.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libnm-util.so.2.6.0
/usr/lib/x86_64-linux-gnu/libnm-util.so.2.6.0