CVE-2026-93251 ACPI: bus: Introduce acpi_bus_get_primary_device()
A use-after-free vulnerability in the Linux kernel ACPI bus allows local attackers to potentially execute code or escalate privileges via stale device pointers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93251?
CVE-2026-93251 is an use after free vulnerability in Linux, published on 24 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:
ACPI: bus: Introduce acpi_bus_get_primary_device()
The function used for obtaining the first "physical" device for which the given ACPI one is the ACPI companion, acpi_get_first_physical_node(), may return a stale device pointer (mostly in theory) because acpi_unbind_one() may run as a whole after dropping the ACPI device's physical_node_lock in acpi_get_first_physical_node() and before it returns. The last reference to the "physical" device may be dropped then before the pointer to it is returned to the caller.
If that happens and the acpi_get_first_physical_node() caller invokes get_device() on the pointer obtained from it, which is done by the majority of its callers, a use-after-free will occur.
To prepare for addressing this problem, introduce a new function for getting the first "physical" device associated with the given ACPI one (the "primary physical device") that will also reference count the device in question before returning a pointer to it.
Make that new function and acpi_get_first_physical_node() share the physical node list lookup code.
No intentional functional impact.
Which versions are affected by CVE-2026-93251?
How do I fix CVE-2026-93251?
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-2026-93251 being exploited?
There is no known exploitation of CVE-2026-93251 in the wild and no public exploit code.
Sources
Also known as AZL-103826, BELL-CVE-2026-93251, DEBIAN-CVE-2026-93251, GHSA-2qvg-p8g6-fm8w, UBUNTU-CVE-2026-93251.