# CVE-2026-80620: Revert "PCI/MSI: Unmap MSI-X region on error"

> A double unmap of a NULL pointer in the Linux kernel MSI-X error path causes a kernel warning and potential denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80620, DEBIAN-CVE-2026-80620, GHSA-wrw8-wwxf-qp7r, UBUNTU-CVE-2026-80620

## What is CVE-2026-80620?

CVE-2026-80620 is a vulnerability in Linux, published on 28 Aug 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:

Revert "PCI/MSI: Unmap MSI-X region on error"

This reverts commit 1a8d4c6ecb4c81261bcdf13556abd4a958eca202.

Commit 1a8d4c6ecb4c ("PCI/MSI: Unmap MSI-X region on error") added an
iounmap(dev->msix_base) on the error path of msix_capability_init() to
release the MSI-X region when msix_setup_interrupts() fails.

When msix_setup_interrupts() fails, the call chain is:

  msix_setup_interrupts()
    -> __msix_setup_interrupts()
         struct pci_dev *dev __free(free_msi_irqs) = __dev;
         ...
         return ret;  // __free cleanup fires on error

The __free(free_msi_irqs) cleanup calls pci_free_msi_irqs(), which
already handles the unmap:

  void pci_free_msi_irqs(struct pci_dev *dev)
  {
      pci_msi_teardown_msi_irqs(dev);
      if (dev->msix_base) {
          iounmap(dev->msix_base);   // already unmapped here
          dev->msix_base = NULL;     // and set to NULL
      }
  }

So dev->msix_base is unmapped and set to NULL before
msix_setup_interrupts() returns to msix_capability_init(). The
"goto out_unmap" introduced by commit 1a8d4c6ecb4c ("PCI/MSI: Unmap
MSI-X region on error") then calls iounmap() a second time on a NULL
pointer.

This was reproduced on Intel Emerald Rapids (192 CPUs) while
running tools/testing/selftests/kexec/test_kexec_jump.sh:

  WARNING: CPU#44 at iounmap+0x2a/0xe0
  RIP: 0010:iounmap+0x2a/0xe0
  RDI: 0000000000000000
  Call Trace:
   msix_capability_init+0x317/0x3f0
   __pci_enable_msix_range+0x21d/0x2c0
   pci_alloc_irq_vectors_affinity+0xa9/0x130
   nvme_setup_io_queues+0x2a8/0x420 [nvme]
   nvme_reset_work+0x151/0x340 [nvme]
   ...

RDI=0 confirms iounmap() is called with NULL.

Restore the original "goto out_disable" and leave the unmap to the
existing __free(free_msi_irqs) cleanup.

## Which versions are affected by CVE-2026-80620?


## How do I fix CVE-2026-80620?

Apply the vendor's patch.

## Is CVE-2026-80620 being exploited?

There is no known exploitation of CVE-2026-80620 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80620 and fix it if it is affected.

What it is: CVE-2026-80620 is a vulnerability in Linux, published on 28 Aug 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-2026-80620 in the wild and no public exploit code.

Affected product: Linux. 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-2026-80620/ (Markdown: https://insights.sbomify.com/CVE-2026-80620/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80620
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80620
- OSV: https://osv.dev/vulnerability/CVE-2026-80620

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80620/
Summaries are generated and may contain mistakes; the official description above is the record.