Cross-site scripting (XSS) vulnerability in the legacy theme preview implementation in wp-includes/theme.php in WordPress before 4.2.4 allows remote attackers to inject arbitrary web script or HTML via a crafted string.
https://wpvulndb.com/vulnerabilities/8133
https://wordpress.org/news/2015/08/wordpress-4-2-4-security-and-maintenance-release/
https://core.trac.wordpress.org/changeset/33549
https://codex.wordpress.org/Version_4.2.4
https://blog.sucuri.net/2015/08/persistent-xss-vulnerability-in-wordpress-explained.html
http://www.securitytracker.com/id/1033178
http://www.securityfocus.com/bid/76331
http://www.debian.org/security/2015/dsa-3383