/usr/lib/x86_64-linux-gnu/libcmrt.so is in libcmrt-dev 1.0.6+dfsg1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libcmrt.so.1.1001.0
/usr/lib/x86_64-linux-gnu/libcmrt.so.1.1001.0