Currently, XFO performs a same origin check only against the top-level frame in a document's ancestor chain. As lcamtuf notes in [1], "Any site that allows a rogue ad to be displayed in an IFRAME; or that frames third-party content for other reasons (e.g., iGoogle, Image Search results, Facebook gadgets), is effectively not protected)." We should check all ancestors instead.



Specification link

Final published standard: Recommendation, Living Standard, Candidate Recommendation, or similar final form

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • Positive
  • No signal
  • No signals


Last updated on 2021-09-24