/usr/lib/x86_64-linux-gnu/octave/ is in octave-sundials 2.5.0-3+b1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/octave/site/
/usr/lib/x86_64-linux-gnu/octave/site/exec/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/cvodes/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/cvodes/cvm/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/cvodes/cvm/cvm.mex
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/idas/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/idas/idm/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/idas/idm/idm.mex
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/kinsol/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/kinsol/kim/
/usr/lib/x86_64-linux-gnu/octave/site/exec/x86_64-pc-linux-gnu/sundialsTB/kinsol/kim/kim.mex