Scenario:
Both pages and the iFrame content are from the same domain.
If the hyperlink in page1 has target="_blank" rel="noopener noreferrer" then the iFrame in page2 can access window.parent.
If the hyperlink in page2 has target="my-tab-name" then the iFrame in page2 crashes when it tries to access any properties of window.parent.
This does not happen in chrome, it only happens when the page is loaded in a CefSharp browser. I inherited the C# code so I don't know if I'm missing some settings, but I can't see anything obvious.