# CVE-2026-43319: spi: spidev: fix lock inversion between spi_lock and buf_lock

> A lock inversion in the Linux kernel spidev driver allows local attackers to cause a deadlock and denial of service via concurrent write and ioctl calls.

- **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:** 1 Jun 2026
- **Also known as:** AZL-86157, BELL-CVE-2026-43319, DEBIAN-CVE-2026-43319, GHSA-p22q-5w3q-wqpq, ROOT-OS-DEBIAN-11-CVE-2026-43319, ROOT-OS-DEBIAN-12-CVE-2026-43319, ROOT-OS-UBUNTU-2204-CVE-2026-43319, ROOT-OS-UBUNTU-2404-CVE-2026-43319, UBUNTU-CVE-2026-43319

## What is CVE-2026-43319?

CVE-2026-43319 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:

spi: spidev: fix lock inversion between spi_lock and buf_lock

The spidev driver previously used two mutexes, spi_lock and buf_lock,
but acquired them in different orders depending on the code path:

  write()/read(): buf_lock -> spi_lock
  ioctl():       spi_lock -> buf_lock

This AB-BA locking pattern triggers lockdep warnings and can
cause real deadlocks:

  WARNING: possible circular locking dependency detected
  spidev_ioctl() -> mutex_lock(&spidev->buf_lock)
  spidev_sync_write() -> mutex_lock(&spidev->spi_lock)
  *** DEADLOCK ***

The issue is reproducible with a simple userspace program that
performs write() and SPI_IOC_WR_MAX_SPEED_HZ ioctl() calls from
separate threads on the same spidev file descriptor.

Fix this by simplifying the locking model and removing the lock
inversion entirely. spidev_sync() no longer performs any locking,
and all callers serialize access using spi_lock.

buf_lock is removed since its functionality is fully covered by
spi_lock, eliminating the possibility of lock ordering issues.

This removes the lock inversion and prevents deadlocks without
changing userspace ABI or behaviour.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-43319?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43319?

Apply the vendor's patch.

## Is CVE-2026-43319 being exploited?

There is no known exploitation of CVE-2026-43319 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-2026-43319 and fix it if it is affected.

What it is: CVE-2026-43319 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-2026-43319 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-2026-43319/ (Markdown: https://insights.sbomify.com/CVE-2026-43319/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43319
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43319
- OSV: https://osv.dev/vulnerability/CVE-2026-43319

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43319/
Summaries are generated and may contain mistakes; the official description above is the record.