General: Validate host on "Are you sure?" screen.

Props voldemortensen, xknown, peterwiloncc.


git-svn-id: https://develop.svn.wordpress.org/trunk@54522 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/functions.php

@@ -3584,10 +3584,12 @@ function wp_nonce_ays( $action ) {
 	} else {
 		$html = __( 'The link you followed has expired.' );
 		if ( wp_get_referer() ) {
+			$wp_http_referer = remove_query_arg( 'updated', wp_get_referer() );
+			$wp_http_referer = wp_validate_redirect( esc_url_raw( $wp_http_referer ) );
 			$html .= '</p><p>';
 			$html .= sprintf(
 				'<a href="%s">%s</a>',
-				esc_url( remove_query_arg( 'updated', wp_get_referer() ) ),
+				esc_url( $wp_http_referer ),
 				__( 'Please try again.' )
 			);
 		}