Directory traversal vulnerability in the File_Upload_Upgrader class in wp-admin/includes/class-file-upload-upgrader.php in the upgrade package uploader in WordPress before 4.6.1 allows remote authenticated users to access arbitrary files via a crafted urlholder parameter.
https://wpvulndb.com/vulnerabilities/8616
https://wordpress.org/news/2016/09/wordpress-4-6-1-security-and-maintenance-release/
https://github.com/WordPress/WordPress/commit/54720a14d85bc1197ded7cb09bd3ea790caa0b6e
https://codex.wordpress.org/Version_4.6.1