CVE-2018-12895: Path Traversal

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 wpdeleteattachment 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.