AMD CPU (Zenbleed): Zenbleed: cross-process/cross-VM register-file data leak on Zen 2 at ~30 kB/s per core, no special

CVSS 6.5CVE-2023-20593Kernel, userspace & hypervisorcurated

Impact

Zenbleed: cross-process/cross-VM register-file data leak on Zen 2 at ~30 kB/s per core, no special privileges

Who can reach it

Any tenant process in a container; tenant VM guest

What to do

AMD microcode (AGESA) update + reboot; kernel chicken-bit workaround (DE_CFG[9]) available with a measured perf cost. Zen 2 EPYC is still common as the CPU side of A100/L40S nodes

Fleet impact

How widespread

common - Zen 2 EPYC (Rome) still hosts a large installed base of GPU nodes and rental fleets

Cost to remediate

microcode+reboot for the real fix; the interim DE_CFG MSR chicken-bit workaround is a kernel change with a measurable FP/vector performance cost - so the fleet either reboots for microcode or eats a permanent tax

Why it hits the whole fleet

Leaks ~30 KB/s/core of stale vector-register data across any privilege boundary including cross-process and cross-VM, i.e. exactly the co-tenancy isolation a GPU cloud sells, on every Rome host at once.

References

https://access.redhat.com/security/cve/CVE-2023-20593

This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.