Index: src/wp-admin/includes/class-wp-site-health.php
===================================================================
--- src/wp-admin/includes/class-wp-site-health.php	(revision 48606)
+++ src/wp-admin/includes/class-wp-site-health.php	(working copy)
@@ -1969,7 +1969,7 @@
 					/* translators: 1: The HTTP error code. 2: The HTTP error message. */
 					__( 'The REST API call gave the following unexpected result: (%1$d) %2$s.' ),
 					wp_remote_retrieve_response_code( $r ),
-					wp_remote_retrieve_body( $r )
+					esc_html( wp_remote_retrieve_body( $r ) )
 				)
 			);
 		} else {