Support in current browsers

Checked against the current browser versions recorded in MDN browser data 8.0.7.

BrowserMinimumOutcomeReason
Chrome150WorksEvery required mapped BCD feature is available without a recorded qualification.
Edge150WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox152WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari26.5Not supportedAt least one required mapped feature is not available at this browser baseline.
Chrome for Android150WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox for Android152WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari on iOS26.5Not supportedAt least one required mapped feature is not available at this browser baseline.
Android WebView150WorksEvery required mapped BCD feature is available without a recorded qualification.
Samsung Internet29.0Not supportedAt least one required mapped feature is not available at this browser baseline.

What this feature can and cannot do

Helps protect against

  • Cookie scope confusion
  • Insecure cookie replacement

Does not guarantee

  • All cookie tossing
  • Cross-site scripting
  • Weak session design

What you need before using it

  • HTTPS
  • Correct Secure, Path, and Domain attributes

Fallback to keep in place

Use host-only Secure cookies with narrow scope and server-side session controls.