# CVE-2026-64588: fuse-uring: fix data races on ring->ready

> A data race in the Linux kernel's fuse-uring module allows stale pointer usage, potentially leading to code execution or privilege escalation.

- **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 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64588, DEBIAN-CVE-2026-64588, GHSA-ww4g-j47r-8q39, UBUNTU-CVE-2026-64588

## What is CVE-2026-64588?

CVE-2026-64588 is a high-severity vulnerability in Linux, published on 6 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:

fuse-uring: fix data races on ring->ready

On weakly-ordered architectures, the store to fiq->ops can be
reordered past the store to ring->ready, allowing a CPU that sees
ring->ready == true via fuse_uring_ready() to dispatch requests
through a stale fiq->ops pointer. Upgrade the store to
smp_store_release() and the load in fuse_uring_ready() to
smp_load_acquire() so that the preceding WRITE_ONCE(fiq->ops, ...)
is visible to any CPU that observes ring->ready == true.

Additionally, fuse_uring_do_register() publishes ring->ready with
WRITE_ONCE() but the fast-path check reads it with a plain load.
This is a marked-vs-unmarked access that KCSAN will flag. Wrap it in
READ_ONCE() to mark it without adding unnecessary ordering.

Also wrap the fc->ring load in fuse_uring_ready() in READ_ONCE() to
prevent the compiler from reloading it between the NULL check and the
dereference.

## Which versions are affected by CVE-2026-64588?


## How do I fix CVE-2026-64588?

Apply the vendor's patch.

## Is CVE-2026-64588 being exploited?

There is no known exploitation of CVE-2026-64588 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64588 and fix it if it is affected.

What it is: CVE-2026-64588 is a high-severity vulnerability in Linux, published on 6 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-2026-64588 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-2026-64588/ (Markdown: https://insights.sbomify.com/CVE-2026-64588/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64588
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64588
- OSV: https://osv.dev/vulnerability/CVE-2026-64588

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64588/
Summaries are generated and may contain mistakes; the official description above is the record.