Database/Kernel, userspace & hypervisor
Intel CPU (Reptar): Redundant REX-prefix MOVSB causes unpredictable behaviour
Impact
Redundant REX-prefix MOVSB causes unpredictable behaviour - a guest can hang or crash the entire host, with possible privilege escalation
Who can reach it
Any tenant process in a container; tenant VM guest
What to do
Microcode update + reboot. Pure availability risk for a neocloud: one tenant can take down a whole node
Fleet impact
How widespread
very common - broad recent Intel Xeon coverage, the host CPU under most NVIDIA GPU nodes
Cost to remediate
microcode+reboot - Intel shipped microcode, but on many platforms it only lands via a BIOS/UEFI update from the OEM, adding an OEM-image dependency on top of the reboot
Why it hits the whole fleet
An unprivileged instruction sequence can hang or machine-check the host, or potentially escalate privilege - so a single tenant can crash a whole GPU node, and the same instruction works on every node of that Xeon generation.
References
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.