CVE-2018-12895

WordPress through 4.9.6 allows Author users to execute arbitrary code by
leveraging directory traversal in the wp-admin/post.php thumb parameter,
which is passed to the PHP unlink function and can delete the wp-config.php
file. This is related to missing filename validation in the
wp-includes/post.php wp_delete_attachment function. The attacker must have
capabilities for files and posts that are normally available only to the
Author, Editor, and Administrator roles. The attack methodology is to
delete wp-config.php and then launch a new installation process to increase
the attacker’s privileges.