Onblur

ID Attribute

October 1, 2020

The id attribute is widely used to identify HTML elements. Unfortunately, cross-origin websites can determine whether a given id is set anywhere on a page by leveraging the focus event and URL fragments. If https://example.com/foo#bar is loaded, the browser attempts to scroll to the element with id="bar". This can be detected cross-origin by loading https://example.com/foo#bar in an iframe; if there is an element with id="bar", the focus event fires. The blur event can also be used for the same purpose 1. ...

Scroll to Text Fragment

October 1, 2020

Scroll to Text Fragment (STTF) is a new web platform feature that allows users to create a link to any part of a web page text. The fragment #:~:text= carries a text snippet that is highlighted and brought into the viewport by the browser. This feature can introduce a new XS-Leak if attackers are able to detect when this behavior occurs. This issue is very similar to the Scroll to CSS Selector XS-Leak. ...