AIKIDO-2026-920595

TL;DR

The JavaScript-backed ReadableStream implementation in workerd runs a stream's pull() callback while delivering a draining read result through an internal event. When pull() aborts the in-flight request during that draining read, the pump's coroutine frame is destroyed from inside the still-firing event, and the runtime aborts the whole process with a fatal Promise callback destroyed itself error. A request that triggers this abort can terminate the workerd process and take down other isolates sharing it, causing a denial of service. The fix moves the pump's isolate-lock work onto the request's task set and reaches the reader through a weak reference so dropping the pump no longer destroys a firing event or runs against a freed reader.