← WebKit Silent-Fix Report — 2026-W23

ceb4d817be51a2f1fd44eb46cd575598358abbdc  [Site Isolation] Approve file URLs from the back-forward target item on the new process, and tighten BrowsingContextGroup processMap invariants

severity medium class Bypass confidence 0.55 Site Isolation History
Basuke Suzuki Wed Jun 3 18:47:09 2026 -0700 full: ceb4d817be51a2f1fd44eb46cd575598358abbdc bug report ↗ view on GitHub ↗
Primitive: Tighten file URL approval for back-forward navigation across processes under site isolation
Triage note: Message and tests (history-back-initial-vs-final-url, file:// back-forward) show the change approves file URLs from the back-forward target item on the new process and tightens the check, addressing which process is authorized to load local file URLs during BF navigation.

Security-relevant, below the exploitable-grade bar for a full root-cause writeup. The triage verdict is above; the side-by-side patch is below.

Before / after

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