Local data inference via stale transient code

Speculative Code Store Bypass in Intel Processors allows local users to infer data during transient execution of self-modifying code. A JIT or other self-modifying-code environment stores new instruction bytes and executes them without serialization, so the processor transiently fetches and runs stale code before observing the store. Low-privileged local code and an affected processor are required; the bounded consequence is data inference through a microarchitectural covert channel, without integrity or availability impact.