/usr/share/xml/entities/xhtml/xhtml-special.ent is in w3c-sgml-lib 1.2-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/xml/entities/xhtml/../../xhtml/schema/dtd/REC-xhtml-modularization-20100729/xhtml-special.ent