# CVE-2026-80858: fuse: publish io-uring queues with release semantics

> A race condition in the Linux kernel FUSE io-uring implementation allows concurrent access to uninitialized memory, potentially causing crashes or code execution.

- **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-2026-80858, DEBIAN-CVE-2026-80858, GHSA-4ch4-gxg4-33mh, UBUNTU-CVE-2026-80858

## What is CVE-2026-80858?

CVE-2026-80858 is a 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:

fuse: publish io-uring queues with release semantics

fuse_uring_create_queue() initializes a fuse_ring_queue and then
publishes the pointer into ring->queues[qid] with WRITE_ONCE() under the
fch->lock. There are several readers that may concurrently be fetching
that pointer locklessly and then deferencing it.

WRITE_ONCE() doesn't ensure ordering of the queue's field
initialization before the ring->queues[qid] pointer assignment. The
queue must be published with smp_store_release() so the field
initialization is guaranteed to happen before.

Readers in paths where the read may happen concurrently with the store
need to use READ_ONCE() because any race involving a plain access is
undefined.

## Which versions are affected by CVE-2026-80858?


## How do I fix CVE-2026-80858?

Apply the vendor's patch.

## Is CVE-2026-80858 being exploited?

There is no known exploitation of CVE-2026-80858 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80858 and fix it if it is affected.

What it is: CVE-2026-80858 is a 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-2026-80858 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-2026-80858/ (Markdown: https://insights.sbomify.com/CVE-2026-80858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80858
- OSV: https://osv.dev/vulnerability/CVE-2026-80858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80858/
Summaries are generated and may contain mistakes; the official description above is the record.