CVE-2026-97996 virtio: fix use-after-free in unregister_virtio_device()
A use-after-free in the Linux kernel virtio subsystem allows local attackers to potentially execute code or escalate privileges when unbinding specific virtio devices.
- 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-2026-97996?
CVE-2026-97996 is an use after free vulnerability in Linux, published on 25 Sep 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:
virtio: fix use-after-free in unregister_virtio_device()
device_unregister() is device_del() plus put_device(). When the caller holds no extra reference, that drops the last one and runs the release callback, which for several transports frees the memory the embedded struct virtio_device sits in. unregister_virtio_device() then calls virtio_debug_device_exit(), which reads dev->debugfs_dir out of the freed object.
Affected transports are the ones whose release callback frees and whose remove path takes no reference: virtio_mmio, virtio_vdpa, virtio_uml, mlxbf-tmfifo and virtio_ccw. virtio_pci is unaffected because virtio_pci_remove() brackets the call with get_device() and put_device().
Remove the debugfs entries before the device can go away. They are only accessed through the protected debugfs interface, so debugfs_remove_recursive() waits for in-progress file operations before returning. Tearing them down while the device is still alive is therefore safe.
Reproduced on User-Mode Linux with CONFIG_KASAN and CONFIG_VIRTIO_DEBUG by unbinding a virtio-uml device:
BUG: KASAN: slab-use-after-free in virtio_debug_device_exit+0x36/0x4d Read of size 8 at addr 00000000616e0b10 by task init/1 __asan_report_load8_noabort virtio_debug_device_exit+0x36/0x4d unregister_virtio_device+0x48/0x75 virtio_uml_remove platform_remove device_release_driver_internal unbind_store
Freed by task 1: kfree virtio_uml_release_dev device_release kobject_put put_device device_unregister
With this applied, the report is gone and unbind is clean.
Which versions are affected by CVE-2026-97996?
How do I fix CVE-2026-97996?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-97996 being exploited?
There is no known exploitation of CVE-2026-97996 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-97996, DEBIAN-CVE-2026-97996, GHSA-gfg9-4r2g-565g, UBUNTU-CVE-2026-97996.