# CVE-2026-93251: ACPI: bus: Introduce acpi_bus_get_primary_device()

CVE-2026-93251 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-93251, released September 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-93251
- Priority: Routine
- CVSS: 5.2 (Moderate)
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 24, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-93251

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-93251](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93251.md) | Sep 24, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-93251](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93251.md) | Sep 24, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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