# CVE-2026-43313: ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()

> A NULL pointer dereference in the Linux kernel ACPI processor driver can cause a system crash, requiring a kernel patch to fix.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-43313, DEBIAN-CVE-2026-43313, GHSA-px47-fmm9-rxw4, ROOT-OS-DEBIAN-11-CVE-2026-43313, ROOT-OS-UBUNTU-2204-CVE-2026-43313, ROOT-OS-UBUNTU-2404-CVE-2026-43313, UBUNTU-CVE-2026-43313

## What is CVE-2026-43313?

CVE-2026-43313 is a medium-severity vulnerability in Linux kernel, published on 8 May 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: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()

In acpi_processor_errata_piix4(), the pointer dev is first assigned an IDE
device and then reassigned an ISA device:

  dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB, ...);
  dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB_0, ...);

If the first lookup succeeds but the second fails, dev becomes NULL. This
leads to a potential null-pointer dereference when dev_dbg() is called:

  if (errata.piix4.bmisx)
    dev_dbg(&dev->dev, ...);

To prevent this, use two temporary pointers and retrieve each device
independently, avoiding overwriting dev with a possible NULL value.

[ rjw: Subject adjustment, added an empty code line ]

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-43313?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43313?

Apply the vendor's patch.

## Is CVE-2026-43313 being exploited?

There is no known exploitation of CVE-2026-43313 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43313 and fix it if it is affected.

What it is: CVE-2026-43313 is a medium-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43313 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43313/ (Markdown: https://insights.sbomify.com/CVE-2026-43313/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43313
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43313
- OSV: https://osv.dev/vulnerability/CVE-2026-43313

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43313/
Summaries are generated and may contain mistakes; the official description above is the record.