In WordPress before 4.7.3 (wp-includes/pluggable.php), control characters can trick redirect URL validation.
{ "binaries": [ { "binary_name": "wordpress", "binary_version": "4.4.2+dfsg-1ubuntu1" }, { "binary_name": "wordpress-l10n", "binary_version": "4.4.2+dfsg-1ubuntu1" }, { "binary_name": "wordpress-theme-twentyfifteen", "binary_version": "4.4.2+dfsg-1ubuntu1" }, { "binary_name": "wordpress-theme-twentyfourteen", "binary_version": "4.4.2+dfsg-1ubuntu1" }, { "binary_name": "wordpress-theme-twentysixteen", "binary_version": "4.4.2+dfsg-1ubuntu1" } ] }