# CVE-2026-93829: smb: client: fix races in cifsd thread creation

> A race condition in the Linux kernel SMB client allows remote attackers to cause a denial of service by triggering a thread synchronization error.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 3 Oct 2026
- **Also known as:** AZL-103769, BELL-CVE-2026-93829, DEBIAN-CVE-2026-93829, GHSA-v43p-8x6p-65w4, UBUNTU-CVE-2026-93829

## What is CVE-2026-93829?

CVE-2026-93829 is a vulnerability in Linux, published on 24 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:

smb: client: fix races in cifsd thread creation

The cifsd demultiplex thread can run and access tcp_ses before the parent
thread has finished populating tcp_ses, which the worker thread accesses
locklessly.

Also, the kthread_run macro may start the thread before returning the
thread pointer. Because the pointer is part of the structure that the
thread can access, if the kernel is preempted after the thread is spawned,
but before the thread pointer is populated and the thread attempts to exit,
it will sleep, waiting for a SIGKILL signal.

Fix this by moving creation of the thread to after all of tcp_ses'es
fields are populated, and spawning the thread last, using a split
kthread_create/wake_up_process logic.

## Which versions are affected by CVE-2026-93829?


## How do I fix CVE-2026-93829?

Apply the vendor's patch.

## Is CVE-2026-93829 being exploited?

There is no known exploitation of CVE-2026-93829 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93829 and fix it if it is affected.

What it is: CVE-2026-93829 is a vulnerability in Linux, published on 24 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-2026-93829 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-2026-93829/ (Markdown: https://insights.sbomify.com/CVE-2026-93829/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93829
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93829
- OSV: https://osv.dev/vulnerability/CVE-2026-93829

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93829/
Summaries are generated and may contain mistakes; the official description above is the record.