CVE-2026-98309 drm/vc4: Use managed KMS polling to fix UAF on unbind
A use-after-free vulnerability in the Linux kernel vc4 driver allows local attackers with root privileges to cause a system crash or potentially execute code during device unbinding.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98309?
CVE-2026-98309 is an use after free vulnerability in Linux, published on 6 Oct 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:
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.
Which versions are affected by CVE-2026-98309?
How do I fix CVE-2026-98309?
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-2026-98309 being exploited?
There is no known exploitation of CVE-2026-98309 in the wild and no public exploit code.
Sources
Also known as AZL-106062, BELL-CVE-2026-98309, DEBIAN-CVE-2026-98309, GHSA-fcmj-9h4r-58r4, UBUNTU-CVE-2026-98309.