Linux Kernel up to 7.2.5 ACPI Bus use after free

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 7.2.5. The impacted element is the function acpi_get_first_physical_node/acpi_bus_get_primary_device of the component ACPI Bus. This manipulation causes use after free. This vulnerability is handled as CVE-2026-93251. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.5. It has been declared as very critical. Affected by this vulnerability is the function acpi_get_first_physical_node/acpi_bus_get_primary_device of the component ACPI Bus. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-93251 since 09/17/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/24/2026).

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch 5657859851abb65105220a6cdb5804926249f714/72530e1f72b0515a73fd88292254d04fecf03649 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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