In WordPress before 4.7.3 (wp-includes/pluggable.php), control characters can trick redirect URL validation.
https://wpvulndb.com/vulnerabilities/8766
https://wordpress.org/news/2017/03/wordpress-4-7-3-security-and-maintenance-release/
https://github.com/WordPress/WordPress/commit/288cd469396cfe7055972b457eb589cea51ce40e
https://codex.wordpress.org/Version_4.7.3
http://www.securitytracker.com/id/1037959