# CVE-2026-90235: sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE

> A race condition in Linux kernel SUNRPC socket callbacks allows stale pointers to be invoked, potentially leading to code execution or denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101885, BELL-CVE-2026-90235, DEBIAN-CVE-2026-90235, GHSA-872w-99m8-9923, UBUNTU-CVE-2026-90235

## What is CVE-2026-90235?

CVE-2026-90235 is a critical vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE

xprtsock replaces and restores sk->sk_data_ready and
sk->sk_write_space on live sockets with plain stores, and
xs_udp_do_set_buffer_size() invokes sk->sk_write_space via a plain
load. These callback pointers are shared with generic socket and
protocol paths that may read or invoke them concurrently, so xprtsock
needs the same READ_ONCE()/WRITE_ONCE() callback visibility contract
that the validated 4022 family applied elsewhere.

When SUNRPC takes over an AF_LOCAL, UDP, or TCP socket and later
restores the lower-socket callbacks during teardown, another CPU may
still hold an earlier callback snapshot. The plain replace/restore
pattern leaves the same visibility hole as the validated 4022 family,
so a stale snapshot can still invoke xs_data_ready() or
xs_udp_write_space() after the live callback fields have already been
restored to the lower-socket handlers.

Use WRITE_ONCE() for the shared sk_data_ready and sk_write_space
stores in xs_local_finish_connecting(), xs_udp_finish_connecting(),
xs_tcp_finish_connecting(), and xs_restore_old_callbacks(). Use
READ_ONCE() for the direct sk_write_space invocation in
xs_udp_do_set_buffer_size(). This matches the required callback
visibility contract while leaving adjacent sk_state_change and
sk_error_report handling unchanged.

## Which versions are affected by CVE-2026-90235?


## How do I fix CVE-2026-90235?

Apply the vendor's patch.

## Is CVE-2026-90235 being exploited?

There is no known exploitation of CVE-2026-90235 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90235 and fix it if it is affected.

What it is: CVE-2026-90235 is a critical vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90235 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-2026-90235/ (Markdown: https://insights.sbomify.com/CVE-2026-90235/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90235
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90235
- OSV: https://osv.dev/vulnerability/CVE-2026-90235

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90235/
Summaries are generated and may contain mistakes; the official description above is the record.