90004-1—Insufficient Site Isolation Against Spectre Vulnerability

Cross-Origin-Resource-Policy header is an opt-in header designed to counter side-channels attacks like Spectre. Resource should be specifically set as shareable amongst different origins.

Ensure that the application/web server sets the Cross-Origin-Resource-Policy header appropriately, and that it sets the Cross-Origin-Resource-Policy header to 'same-origin' for all web pages. 'same-site' is considered as less secured and should be avoided. If resources must be shared, set the header to 'cross-origin'. If possible, ensure that the end user uses a standards-compliant and modern web browser that supports the Cross-Origin-Resource-Policy header (https://caniuse.com/mdn-http_headers_cross-origin-resource-policy).