Cross-site scripting (XSS) vulnerability in wp-includes/wp-db.php in WordPress before 4.2.2 allows remote attackers to inject arbitrary web script or HTML via a long comment that is improperly stored because of limitations on the MySQL TEXT data type. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-3440.
https://wordpress.org/news/2015/05/wordpress-4-2-2/