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src/compiler/compile/nodes/Element.ts

@@ -621,7 +621,10 @@ export default class Element extends Node {
 			const name_attribute = attribute_map.get('name');
 			const target_attribute = attribute_map.get('target');
 
-			if (component.compile_options.legacy && target_attribute && target_attribute.get_static_value() === '_blank' && href_attribute) {
+			// links with target="_blank" should have no opener or noreferrer: https://developer.chrome.com/docs/lighthouse/best-practices/external-anchors-use-rel-noopener/
+			// modern browsers add noopener by default, so we only need to check legacy browsers
+			// legacy browsers don't support noopener so we only check for noreferrer there
+			If (component.compile_options.legacy && target_attribute && target_attribute.get_static_value() === '_blank' && href_attribute) {
 				const href_static_value = href_attribute.get_static_value() ? href_attribute.get_static_value().toLowerCase() : null;
 
 				if (href_static_value === null || href_static_value.match(/^(https?:)?\/\//i)) {