/usr/include/CGAL/Mesh_3/ is in libcgal-dev 4.2-5ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Mesh_3/C3T3_helpers.h
/usr/include/CGAL/Mesh_3/Cell_criteria_visitor_with_balls.h
/usr/include/CGAL/Mesh_3/Creator_weighted_point_3.h
/usr/include/CGAL/Mesh_3/Detect_features_in_polyhedra.h
/usr/include/CGAL/Mesh_3/Detect_features_in_polyhedra_fwd.h
/usr/include/CGAL/Mesh_3/Detect_polylines_in_polyhedra.h
/usr/include/CGAL/Mesh_3/Detect_polylines_in_polyhedra_fwd.h
/usr/include/CGAL/Mesh_3/Facet_criteria_visitor_with_balls.h
/usr/include/CGAL/Mesh_3/Facet_on_same_surface_criterion.h
/usr/include/CGAL/Mesh_3/IO.h
/usr/include/CGAL/Mesh_3/Image_to_labeled_function_wrapper.h
/usr/include/CGAL/Mesh_3/Implicit_surface_mesher_visitor.h
/usr/include/CGAL/Mesh_3/Labeled_mesh_domain_3.h
/usr/include/CGAL/Mesh_3/Lloyd_move.h
/usr/include/CGAL/Mesh_3/Mesh_complex_3_in_triangulation_3_base.h
/usr/include/CGAL/Mesh_3/Mesh_global_optimizer.h
/usr/include/CGAL/Mesh_3/Mesh_sizing_field.h
/usr/include/CGAL/Mesh_3/Mesh_surface_cell_base_3.h
/usr/include/CGAL/Mesh_3/Mesher_3.h
/usr/include/CGAL/Mesh_3/Null_exuder_visitor.h
/usr/include/CGAL/Mesh_3/Null_global_optimizer_visitor.h
/usr/include/CGAL/Mesh_3/Null_perturber_visitor.h
/usr/include/CGAL/Mesh_3/Odt_move.h
/usr/include/CGAL/Mesh_3/Poisson_refine_cells_3.h
/usr/include/CGAL/Mesh_3/Polyline_with_context.h
/usr/include/CGAL/Mesh_3/Protect_edges_sizing_field.h
/usr/include/CGAL/Mesh_3/Refine_cells_3.h
/usr/include/CGAL/Mesh_3/Refine_facets_3.h
/usr/include/CGAL/Mesh_3/Refine_tets_visitor.h
/usr/include/CGAL/Mesh_3/Robust_intersection_traits_3.h
/usr/include/CGAL/Mesh_3/Robust_weighted_circumcenter_filtered_traits_3.h
/usr/include/CGAL/Mesh_3/Sizing_grid.h
/usr/include/CGAL/Mesh_3/Sliver_perturber.h
/usr/include/CGAL/Mesh_3/Slivers_exuder.h
/usr/include/CGAL/Mesh_3/Slivers_exuder_cell_attributes_traits.h
/usr/include/CGAL/Mesh_3/Triangle_accessor_primitive.h
/usr/include/CGAL/Mesh_3/Triangulation_helpers.h
/usr/include/CGAL/Mesh_3/Triangulation_sizing_field.h
/usr/include/CGAL/Mesh_3/Uniform_sizing_field.h
/usr/include/CGAL/Mesh_3/dihedral_angle_3.h
/usr/include/CGAL/Mesh_3/global_parameters.h
/usr/include/CGAL/Mesh_3/implicit_to_labeled_function_wrapper.h
/usr/include/CGAL/Mesh_3/mesh_standard_cell_criteria.h
/usr/include/CGAL/Mesh_3/mesh_standard_criteria.h
/usr/include/CGAL/Mesh_3/mesh_standard_facet_criteria.h
/usr/include/CGAL/Mesh_3/min_dihedral_angle.h
/usr/include/CGAL/Mesh_3/parameters_defaults.h
/usr/include/CGAL/Mesh_3/polyhedral_to_labeled_function_wrapper.h
/usr/include/CGAL/Mesh_3/radius_ratio.h
/usr/include/CGAL/Mesh_3/sliver_criteria.h
/usr/include/CGAL/Mesh_3/utilities.h
/usr/include/CGAL/Mesh_3/vertex_perturbation.h