Feature: #78488 - Add rel="noreferrer" to external links

Description

All links processed by typolink with external links opening in a new window have been extended to contain rel="noreferrer".

Links opening in a new window are defined as those having an attribute target which is either not empty, _self, _top or _parent.

Note

Initially this feature added rel="noopener noreferrer. However noreferrer also implies the property noopener. Therefore, the latter was removed.

Impact

This property improves the security of the site:

noreferrer: This property prevents the browser, when navigating to another page, to send the page address, or any other value, as referrer in according HTTP header. noreferrer also implies the property noopener, which instructs the browser to open the link without granting the new browsing context access to the document that opened it.