Chrome 141/Firefox 140 storage access activation per origin by chrisdavidmills · Pull Request #28682 · mdn/browser-compat-data

chrisdavidmills · 2025-12-16T16:59:49Z

Summary

While using the Storage Access API, when embedded content activates a previously-granted storage-access permission via the requestStorageAccess() method, 3rd party cookies are now only sent with requests to the calling embed's exact origin.

Previously, 3rd party cookies were sent with requests to the calling embed's site.

This behavioral change has occurred in:

Chrome 141: See https://chromestatus.com/feature/5169937372676096.
Firefox 140: See https://wpt.fyi/results/storage-access-api/requestStorageAccess-cross-origin-fetch.sub.https.window.html?run_id=5176618970775552

This PR adds notes in relevant places to document this change.

cc @cfredric / @hamishwillee — I'd appreciate your input on this one, folks.

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Related issues

github-actions · 2025-12-16T17:00:27Z

Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

http/headers/Activate-Storage-Access.json

Co-authored-by: Chris Fredrickson <cfredric@users.noreply.github.com>

cfredric

Chrome details LGTM!

chrisdavidmills · 2026-01-05T12:14:27Z

Hi @caugner! Do you have time to look at this one?

api/Document.json

caugner

Should we actually move this into a behavioral subfeature? (This sounds like a spec change!?)

caugner · 2026-01-14T17:25:06Z

api/Document.json

            "firefox": {
-              "version_added": "65"
+              "version_added": "65",
+              "notes": "From version 140 onwards, activating the `storage-access` permission via `requestStorageAccess()` results in third-party cookies being sent only with requests to the calling embed's exact origin (see [bug 1965817](https://bugzil.la/1965817)). Before version 140, it resulted in third-party cookies being sent with requests to the calling embed's site."


I asked internally for confirmation that this is the right bug.

cfredric · 2026-01-14T22:49:09Z

(This sounds like a spec change!?)

Yup - the corresponding spec change was privacycg/storage-access#213.

caugner · 2026-01-15T08:58:33Z

Yup - the corresponding spec change was privacycg/storage-access#213.

Thanks! Based on that, the subfeature could be called strict_same_origin_policy.

chrisdavidmills · 2026-01-15T09:13:52Z

Yup - the corresponding spec change was privacycg/storage-access#213.

Thanks! Based on that, the subfeature could be called strict_same_origin_policy.

To clarify, how would you represent this in the current setup? This isn't a separate feature; it's represented as notes hanging off the requestStorageAccess() feature.

caugner · 2026-01-15T09:50:49Z

To clarify, how would you represent this in the current setup? This isn't a separate feature; it's represented as notes hanging off the requestStorageAccess() feature.

I would add a subfeature api.Document.requestStorageAccess.strict_same_origin_policy with the description explaining the new behavior.

chrisdavidmills · 2026-01-16T14:00:35Z

To clarify, how would you represent this in the current setup? This isn't a separate feature; it's represented as notes hanging off the requestStorageAccess() feature.

I would add a subfeature api.Document.requestStorageAccess.strict_same_origin_policy with the description explaining the new behavior.

OK, I've done so.

api/Document.json

caugner · 2026-01-16T14:20:18Z

api/Document.json

-              "notes": "Client-side storage access granted per-page ([see explanation](https://developer.mozilla.org/docs/Web/API/Storage_Access_API#how_it_works))"
+              "notes": [
+                "Client-side storage access is granted per-page ([see explanation](https://developer.mozilla.org/docs/Web/API/Storage_Access_API#how_it_works)).",
+                "`storage-access` activation results in third-party cookies being sent with requests to the calling embed's site."


Either this note describes the expected behavior before the spec change (then let's remove this note), or it describes a particular Chrome behavior before the spec change (then let's remove the note to the subfeature).

Rats, I meant to remove that note, but forgot. Removed now.

I also updated the URL on the remaining note line to point directly at the note that explains "granted per-page", as the existing URL wasn't very effective.

Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

Chrome 141/Firefox 140 storage access activation per origin

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github-actions bot added data:http Compat data for HTTP features. https://developer.mozilla.org/docs/Web/HTTP data:api Compat data for Web APIs. https://developer.mozilla.org/docs/Web/API size:s [PR only] 7-24 LoC changed labels Dec 16, 2025

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Update http/headers/Activate-Storage-Access.json

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Co-authored-by: Chris Fredrickson <cfredric@users.noreply.github.com>

github-actions bot removed the data:http Compat data for HTTP features. https://developer.mozilla.org/docs/Web/HTTP label Dec 17, 2025

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Merge branch 'main' into storage-access-activation-per-origin-not-site

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chrisdavidmills added 2 commits January 14, 2026 10:44

Merge branch 'main' into storage-access-activation-per-origin-not-site

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fixes for caugner review comments

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github-actions bot added size:m [PR only] 25-100 LoC changed and removed size:s [PR only] 7-24 LoC changed labels Jan 14, 2026

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revert unwanted changes

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Merge branch 'main' into storage-access-activation-per-origin-not-site

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Add separate strict_same_origin_policy feature

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github-actions bot added size:m [PR only] 25-100 LoC changed and removed size:s [PR only] 7-24 LoC changed labels Jan 16, 2026

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chrisdavidmills and others added 2 commits January 16, 2026 15:20

Update api/Document.json

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Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

Remove note, improve URL

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chrisdavidmills requested a review from caugner January 16, 2026 15:31

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Merge branch 'main' into storage-access-activation-per-origin-not-site

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chrisdavidmills enabled auto-merge (squash) January 19, 2026 11:03

chrisdavidmills disabled auto-merge January 19, 2026 11:03

Fix linting error

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chrisdavidmills merged commit bc5c183 into mdn:main Jan 19, 2026
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chrisdavidmills deleted the storage-access-activation-per-origin-not-site branch January 19, 2026 11:31

mdn-bot mentioned this pull request Jan 19, 2026

Release v7.2.5 #28845

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