CVE-2026-64472 vfio/mlx5: Fix racy bitfields and tighten struct layout
A race condition in the Linux kernel vfio/mlx5 driver allows local attackers to cause denial of service or potentially escalate privileges via concurrent bitfield updates.
- 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-2026-64472?
CVE-2026-64472 is a 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/mlx5: Fix racy bitfields and tighten struct layout
Bitfield operations are not atomic, they use a read-modify-write pattern, therefore we should be careful not to pack bitfields that can be concurrently updated into the same storage unit.
This split takes a binary approach: flags that are only modified pre/post open/close remain bitfields, flags modified from user action, including actions that reach across to another device (ex. reset) use dedicated storage units.
Note mlx5_vhca_page_tracker.status is relocated to fill the alignment hole this split exposes.
Bitfield justifications:
migrate_cap: written only in mlx5vf_cmd_set_migratable() at probe chunk_mode: written only in mlx5vf_cmd_set_migratable() at probe mig_state_cap: written only in mlx5vf_cmd_set_migratable() at probe
Dedicated storage units:
mdev_detach: written in the VF attach/detach event notifier mlx5fv_vf_event() at runtime log_active: written in mlx5vf_start_page_tracker()/ mlx5vf_stop_page_tracker() during runtime dirty tracking deferred_reset: written in mlx5vf_state_mutex_unlock()/ mlx5vf_pci_aer_reset_done() during runtime reset handling is_err: set by tracker error handling and dirty-log polling at runtime object_changed: set by tracker event handling and cleared by dirty-log polling at runtime
Which versions are affected by CVE-2026-64472?
How do I fix CVE-2026-64472?
Apply the vendor's patch.
Is CVE-2026-64472 being exploited?
There is no known exploitation of CVE-2026-64472 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64472, DEBIAN-CVE-2026-64472, GHSA-3wrg-mvh6-9v25, ROOT-OS-UBUNTU-2204-CVE-2026-64472, UBUNTU-CVE-2026-64472.