← WebKit Silent-Fix Report — 2026-W34

4fa207d1c8d4a14afbda9ffa02b9070effd52d9b  [WebCore] Memory underflow in PlatformRawAudioData::copyTo()

severity medium class OOB confidence 0.55 WebCore WebCodecs Audio
Jer Noble Sat Aug 22 15:07:51 2026 -0700 full: 4fa207d1c8d4a14afbda9ffa02b9070effd52d9b bug report ↗ view on GitHub ↗
Primitive: Memory underflow in PlatformRawAudioData::copyTo() with zero frame count
Triage note: copyTo() proceeded with copyElementCount==0 (e.g. frameCount:0), and downstream span/pointer arithmetic underflows on an empty copy. Fix early-returns when !copyElementCount before computing destination spans.

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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