Intent to unship: Cache clearing via the Clear-Site-Data header

[Benjamin VanderSloot]

As of Firefox 94 I intend to remove support for the “cache” value in the Clear-Site-Data header. Status in other browsers is supported in Chrome, Edge, and Opera and unsupported in Safari and IE.

Bug to remove: https://bugzilla.mozilla.org/show_bug.cgi?id=1671182

Allowing a page to clear site data allows for different origins in the same site to interfere or communicate with one another when storage is partitioned. This was the original rationale of WebKit when declining to implement the Clear-Site-Data header at its original creation. Communication has been resolved by restricting the behavior of “cookies” and “storage” to within each origin’s partitioned storage. However, no such obvious choice exists for cache data. As such, discussion led to the proposed removal of support just for “cache.”

Related discussion: https://github.com/privacycg/storage-partitioning/issues/11

Thank you,

Ben VanderSloot