CVE-2026-64474 vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc
A local attacker can trigger an infinite loop in the Linux kernel VFIO migration code, causing a system hang or panic.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64474?
CVE-2026-64474 is a denial of service vulnerability in Linux, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc
vfio_mig_get_next_state() walks vfio_from_fsm_table[] one step at a time, looping to skip optional states the device does not support until *next_fsm is supported. A blocked transition is encoded as VFIO_DEVICE_STATE_ERROR, which the trailing return reports as -EINVAL.
The skip loop does not account for the ERROR sentinel. state_flags_table[ERROR] is ~0U and vfio_from_fsm_table[ERROR][*] is ERROR, so once *next_fsm becomes ERROR the loop condition stays true and *next_fsm never changes. The blocked arcs STOP_COPY -> PRE_COPY and STOP_COPY -> PRE_COPY_P2P map to ERROR yet pass the support check on a precopy-capable device, causing the loop to spin forever while holding the driver state mutex. This can result in a soft lockup, and a panic with softlockup_panic set.
Terminate the skip loop on the ERROR sentinel so a blocked transition falls through to the existing return and reports -EINVAL.
Which versions are affected by CVE-2026-64474?
How do I fix CVE-2026-64474?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-64474 being exploited?
There is no known exploitation of CVE-2026-64474 in the wild and no public exploit code.
Sources
Also known as AZL-93764, BELL-CVE-2026-64474, DEBIAN-CVE-2026-64474, GHSA-67fj-9v49-3ch9, ROOT-OS-UBUNTU-2204-CVE-2026-64474, UBUNTU-CVE-2026-64474.