Remote code execution via TypedArray length overflow

Integer overflow in SerenityOS LibJS before 2021-01-27 allows remote attackers to execute code through crafted browser JavaScript. initialize_typed_array_from_array_buffer multiplies an attacker-controlled array length by the element size and adds the byte offset without checking size_t wraparound, producing a view with out-of-bounds read and write access. A user must load attacker-controlled content in Browser; the published exploit turns the resulting memory primitives into arbitrary code execution in the browser process.