# CVE-2026-80821: nvmet: pci-epf: put CQ ref on create_cq mapping failure

> A remote PCI host can cause a memory leak and controller reference leak in the Linux kernel NVMe PCI endpoint function driver by triggering mapping failures during completion queue creation.

- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80821, DEBIAN-CVE-2026-80821, GHSA-xgj8-pp4r-hmxg, UBUNTU-CVE-2026-80821

## What is CVE-2026-80821?

CVE-2026-80821 is a denial of service vulnerability in Linux, published on 4 Sep 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:

nvmet: pci-epf: put CQ ref on create_cq mapping failure

nvmet_pci_epf_create_cq() calls nvmet_cq_create(), which takes a
reference on the controller and installs the completion queue. If the
subsequent PCI address-space mapping fails or returns a too-small partial
mapping, the function jumps to err_internal / err_unmap_queue without
calling nvmet_cq_put(). The matching put in nvmet_pci_epf_delete_cq() is
gated on NVMET_PCI_EPF_Q_LIVE, which is only set after the mapping
succeeds, so teardown never releases these references. A remote PCI host
that drives Create IO CQ commands with a failing PRP1/pci_addr therefore
leaks the CQ and a controller reference on each attempt.

Drop the CQ reference on the mapping-failure paths. The err_internal and
err_unmap_queue labels are only reachable after nvmet_cq_create() has
succeeded, so this pairs the create/put correctly.

## Which versions are affected by CVE-2026-80821?


## How do I fix CVE-2026-80821?

Apply the vendor's patch.

## Is CVE-2026-80821 being exploited?

There is no known exploitation of CVE-2026-80821 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80821 and fix it if it is affected.

What it is: CVE-2026-80821 is a denial of service vulnerability in Linux, published on 4 Sep 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-2026-80821 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-2026-80821/ (Markdown: https://insights.sbomify.com/CVE-2026-80821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80821
- OSV: https://osv.dev/vulnerability/CVE-2026-80821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80821/
Summaries are generated and may contain mistakes; the official description above is the record.