/usr/share/php/Symfony/Component/Form/Extension/Csrf/ is in php-symfony-form 2.7.10-0ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfExtension.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/CsrfProviderAdapter.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/CsrfProviderInterface.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/CsrfTokenManagerAdapter.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/DefaultCsrfProvider.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/CsrfProvider/SessionCsrfProvider.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/EventListener/
/usr/share/php/Symfony/Component/Form/Extension/Csrf/EventListener/CsrfValidationListener.php
/usr/share/php/Symfony/Component/Form/Extension/Csrf/Type/
/usr/share/php/Symfony/Component/Form/Extension/Csrf/Type/FormTypeCsrfExtension.php