# CVE-2026-43211: PCI: Fix pci_slot_trylock() error handling

> A logic error in Linux kernel PCI slot locking causes incorrect unlock operations, potentially leading to system instability or denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 6 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-43211, DEBIAN-CVE-2026-43211, GHSA-3629-447p-wp7v, ROOT-OS-DEBIAN-11-CVE-2026-43211, ROOT-OS-UBUNTU-2204-CVE-2026-43211, ROOT-OS-UBUNTU-2404-CVE-2026-43211, UBUNTU-CVE-2026-43211

## What is CVE-2026-43211?

CVE-2026-43211 is a high-severity vulnerability in Linux kernel, published on 6 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:

PCI: Fix pci_slot_trylock() error handling

Commit a4e772898f8b ("PCI: Add missing bridge lock to pci_bus_lock()")
delegates the bridge device's pci_dev_trylock() to pci_bus_trylock() in
pci_slot_trylock(), but it forgets to remove the corresponding
pci_dev_unlock() when pci_bus_trylock() fails.

Before a4e772898f8b, the code did:

  if (!pci_dev_trylock(dev)) /* <- lock bridge device */
    goto unlock;
  if (dev->subordinate) {
    if (!pci_bus_trylock(dev->subordinate)) {
      pci_dev_unlock(dev);   /* <- unlock bridge device */
      goto unlock;
    }
  }

After a4e772898f8b the bridge-device lock is no longer taken, but the
pci_dev_unlock(dev) on the failure path was left in place, leading to the
bug.

This yields one of two errors:

  1. A warning that the lock is being unlocked when no one holds it.
  2. An incorrect unlock of a lock that belongs to another thread.

Fix it by removing the now-redundant pci_dev_unlock(dev) on the failure
path.

[Same patch later posted by Keith at
https://patch.msgid.link/20260116184150.3013258-1-kbusch@meta.com]

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-43211?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43211?

Apply the vendor's patch.

## Is CVE-2026-43211 being exploited?

There is no known exploitation of CVE-2026-43211 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-2026-43211 and fix it if it is affected.

What it is: CVE-2026-43211 is a high-severity vulnerability in Linux kernel, published on 6 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-2026-43211 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-2026-43211/ (Markdown: https://insights.sbomify.com/CVE-2026-43211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43211
- OSV: https://osv.dev/vulnerability/CVE-2026-43211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43211/
Summaries are generated and may contain mistakes; the official description above is the record.