← WebKit Silent-Fix Report — 2026-W23

846badc3c41ca797dd2d5980061ad32c157638f5  Add missing null checks when calling internal stream functions

severity low class LogicError confidence 0.55 WebCore Streams
Youenn Fablet Wed Jun 3 00:02:40 2026 -0700 full: 846badc3c41ca797dd2d5980061ad32c157638f5 bug report ↗ view on GitHub ↗
Primitive: Missing null checks on internal stream function return values
Triage note: ReadableStreamDefaultReader::read and StreamPipeToState paths called downcast<JSC::JSPromise> on values that can be null when internal stream functions fail (e.g. worker terminated mid-pipeTo), crashing on null. Fix adds null checks before the downcasts. Reachable DoS only.

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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