A problem in the ECMAScript specification of async generators may lead to mis-implementation in a way that could present as a security issue, such as type confusion and pointer dereference. The internal async generator machinery calls regular promise resolver functions on IteratorResult objects, assuming that these objects will not be then-ables. However, these objects can be made then-able, triggering arbitrary behavior, including re-entering the async generator machinery in a way that violates some internal invariants.