← WebKit Silent-Fix Report — 2026-W21

d55bf0c070  [JSC] WebAssemblyGCStructure::finalizeUnconditionally should be called

severity medium class UAF confidence 0.55 JSC Heap / Wasm GC
Yusuke Suzuki Thu May 21 09:12:37 2026 -0700 full: d55bf0c070cab46177593f16f1bb45fd5cb72de6 bug report ↗ view on GitHub ↗
Primitive: unconditional finalizer never run for WebAssemblyGCStructure
Triage note: A GC-managed structure whose unconditional finalizer never ran can leave stale/unreleased state, a lifetime hazard in the Wasm GC path.

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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