In WordPress before 4.7.5, a cross-site scripting (XSS) vulnerability related to the Customizer exists, involving an invalid customization session.
https://wpvulndb.com/vulnerabilities/8820
https://wordpress.org/news/2017/05/wordpress-4-7-5/
https://github.com/WordPress/WordPress/commit/3d10fef22d788f29aed745b0f5ff6f6baea69af3
https://codex.wordpress.org/Version_4.7.5
http://www.securitytracker.com/id/1038520