Intel processors (register file data sampling): MULTI-TENANT ISOLATION: RFDS: stale data left in the integer

Impact

MULTI-TENANT ISOLATION: RFDS: stale data left in the integer, floating-point and vector register files after transient execution can be sampled by a local attacker, crossing the process, VM and enclave boundaries. Vector register files are where model activations and weights live during compute, so on an AI host this leaks the workload's actual data, not just pointers.

Who can reach it

Local authenticated code on an affected processor, including a co-tenant VM or container.

What to do

Mitigated by an Intel microcode update plus OS/hypervisor changes. Microcode for this class is normally shipped by your distribution as an early-loadable image, so you can deploy it with a package update and a reboot without waiting for an OEM BIOS release - that distinction is the difference between a week and a quarter. Verify after reboot by reading /sys/devices/system/cpu/vulnerabilities/ rather than assuming the package took effect. The kernel-side mitigation reuses the VERW buffer-clearing path, so a current kernel plus current microcode is the whole story; check the reg_file_data_sampling sysfs entry after reboot.

References