Index: src/wp-includes/kses.php
===================================================================
--- src/wp-includes/kses.php	(revision 49504)
+++ src/wp-includes/kses.php	(working copy)
@@ -2171,6 +2171,7 @@
 	 * @since 5.3.0 Added support for `grid`, `flex` and `column` layout properties.
 	 *              Extend `background-*` support of individual properties.
 	 * @since 5.3.1 Added support for gradient backgrounds.
+	 * @since 5.6.0 Added support for `white-space`.
 	 *
 	 * @param string[] $attr Array of allowed CSS attributes.
 	 */
@@ -2232,6 +2233,7 @@
 			'text-decoration',
 			'text-indent',
 			'text-transform',
+			'white-space',
 
 			'height',
 			'min-height',