TLP Rating: Amber 
CERT Vanuatu and the Office of the Chief Information Officer (OGCIO) are giving everyone this international advisory from Intel's advisory centre. We acknowledge the work of Intel with this advisory.
- INTEL-SA-00145: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00145.html
Summary
System software may utilize the Lazy FP state restore technique to delay the restoring of state until an instruction operating on that state is actually executed by the new process. Systems using Intel® Core-based microprocessors may potentially allow a local process to infer data utilizing Lazy FP state restore from another process through a speculative execution side channel.