/usr/share/ is in php-horde-serialize 2.0.5-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/
/usr/share/php/Horde/
/usr/share/php/Horde/Serialize/
/usr/share/php/Horde/Serialize/Exception.php
/usr/share/php/Horde/Serialize.php
/usr/share/php/.registry/
/usr/share/php/.registry/.channel.pear.horde.org/
/usr/share/php/.registry/.channel.pear.horde.org/horde_serialize.reg
/usr/share/doc/
/usr/share/doc/php-horde-serialize/
/usr/share/doc/php-horde-serialize/Horde/
/usr/share/doc/php-horde-serialize/Horde/Serialize/
/usr/share/doc/php-horde-serialize/Horde/Serialize/examples/
/usr/share/doc/php-horde-serialize/Horde/Serialize/examples/json.php
/usr/share/doc/php-horde-serialize/copyright
/usr/share/doc/php-horde-serialize/changelog.Debian.gz
/usr/share/doc/php-horde-serialize/package.xml.gz