In issue 786505 , we added logic to block network responses with cross-site HTML, XML, and JSON documents from the renderer process, but we only enabled it in Site Isolation modes. This logic is necessary for Site Isolation's goals (to prevent leaking sensitive data from other sites), but it's useful to help against cross-site script inclusion (XSSI) attacks as well, even when Site Isolation is not enabled.
This bug tracks enabling the logic in Chrome by default. We'll need to monitor the current stats from blocking to make sure it does not have a compatibility impact, we should send a Blink intent to discuss.
Context:
http://www.chromium.org/developers/design-documents/blocking-cross-site-documentshttps://www.chromium.org/Home/chromium-security/site-isolation#TOC-Recommendations-for-Web-Developers
Comment 1 by nasko@chromium.org
, Mar 2 2018