WordPress before 4.5.3 allows remote attackers to obtain sensitive revision-history information by leveraging the ability to read a post, related to wp-admin/includes/ajax-actions.php and wp-admin/revision.php.
https://wpvulndb.com/vulnerabilities/8519
https://wordpress.org/news/2016/06/wordpress-4-5-3/
https://github.com/WordPress/WordPress/commit/a2904cc3092c391ac7027bc87f7806953d1a25a1
https://codex.wordpress.org/Version_4.5.3
http://www.securitytracker.com/id/1036163