Ticket #44949: 44949.2.patch

src/wp-includes/rest-api.php

@@ -1144 +1144 @@
                 return new WP_Error( 'rest_invalid_param', sprintf( __( '%1$s is not of type %2$s.' ), $param, 'string' ) );
         }
 
+        if ( 'string' === $args['type'] && ! empty( $args['pattern'] ) ) {
+            if ( ! preg_match( $args['pattern'], $value ) ) {
+                    return new WP_Error( 'rest_invalid_pattern', sprintf( __( '%1$s does not match pattern %s$s.' ), $param, $args['pattern'] ) );
+        }
+    }
+
         if ( isset( $args['format'] ) ) {
                 switch ( $args['format'] ) {
                         case 'date-time':