/usr/share/php/Symfony/ is in php-symfony-classloader 2.3.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Symfony/Component/
/usr/share/php/Symfony/Component/ClassLoader/
/usr/share/php/Symfony/Component/ClassLoader/ApcClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/ClassCollectionLoader.php
/usr/share/php/Symfony/Component/ClassLoader/ClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/ClassMapGenerator.php
/usr/share/php/Symfony/Component/ClassLoader/DebugClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/DebugUniversalClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/MapClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/UniversalClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/WinCacheClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/XcacheClassLoader.php
/usr/share/php/Symfony/Component/ClassLoader/autoloader.php