CVE-2026-93251
Received Received - Intake

Use-After-Free in Linux Kernel ACPI Subsystem

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

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.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-93251
EUVD
EUVD-2026-86123

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a use-after-free issue in the ACPI subsystem. The function acpi_get_first_physical_node() may return a stale device pointer, leading to a use-after-free when callers invoke get_device() on it. A new function, acpi_bus_get_primary_device(), has been introduced to address this by properly reference counting the device before returning a pointer.

Detection Guidance

This vulnerability is specific to the Linux kernel's ACPI subsystem and requires kernel-level inspection. Detection involves checking kernel logs for ACPI-related errors or crashes, particularly after system updates or reboots. Commands like dmesg | grep -i acpi or journalctl -k | grep -i acpi may reveal issues. However, no direct detection commands are provided in the context.

Impact Analysis

This vulnerability could lead to system crashes, memory corruption, or potential privilege escalation if exploited. It primarily affects systems using ACPI, which is common in most Linux-based systems. Successful exploitation may allow an attacker to execute arbitrary code or cause denial-of-service conditions.

Mitigation Strategies

Apply the latest kernel updates from your Linux distribution to ensure the patched function acpi_bus_get_primary_device() is included. Reboot the system after updating to activate the changes. Monitor system stability and ACPI-related logs post-update.

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