← WebKit Silent-Fix Report — 2026-W34

cc7a6821b7cceb7cb9e2836a9dfc11a42691683a  REGRESSION(318278@main?)[macOS]: ASSERTION FAILED: !m_waitingForContentPolicy /Volumes/Data/worker/Apple-Tahoe-Debug-Build/build/Source/WebCore/loader/DocumentLoader.cpp

severity medium class LogicError confidence 0.55 WebKit NetworkResourceLoader
Chris Dumez Tue Aug 18 17:29:31 2026 -0700 full: cc7a6821b7cceb7cb9e2836a9dfc11a42691683a bug report ↗ view on GitHub ↗
Primitive: Unserialized multipart/x-mixed-replace response flow control in NetworkResourceLoader
Triage note: CFNetwork delivers multipart parts/data/end without awaiting the prior part's response completion (ContinueDidReceiveResponse), tripping ASSERT(!m_waitingForContentPolicy) and requiring the loader to serialize itself; fix defers messages, caps them (100MB/1024) to bound network-process memory, and cancelDeferredMessages() in the destructor. State-machine/DoS hardening around the content-policy check.

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

Loading diff…