Hyper-Threading Considered Harmful

Hyper-Threading, as currently implemented on Intel Pentium Extreme
Edition, Pentium 4, Mobile Pentium 4, and Xeon processors, suffers from
a serious security flaw. This flaw permits local information
disclosure, including allowing an unprivileged user to steal an RSA
private key being used on the same machine. Administrators of
multi-user systems are strongly advised to take action to disable
Hyper-Threading immediately; single-user systems are not affected.more