# CVE-2026-23230: smb: client: split cached_fid bitfields to avoid shared-byte RMW races

> Concurrent updates to SMB client cached file ID flags can cause race conditions, potentially leading to inconsistent state or undefined behavior.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Feb 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-23230, DEBIAN-CVE-2026-23230, GHSA-p68h-c56f-p3v6, ROOT-OS-DEBIAN-11-CVE-2026-23230, ROOT-OS-DEBIAN-12-CVE-2026-23230, ROOT-OS-UBUNTU-2404-CVE-2026-23230, UBUNTU-CVE-2026-23230

## What is CVE-2026-23230?

CVE-2026-23230 is a high-severity vulnerability in Linux kernel, published on 18 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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

smb: client: split cached_fid bitfields to avoid shared-byte RMW races

is_open, has_lease and on_list are stored in the same bitfield byte in
struct cached_fid but are updated in different code paths that may run
concurrently. Bitfield assignments generate byte read–modify–write
operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can
restore stale values of the others.

A possible interleaving is:
    CPU1: load old byte (has_lease=1, on_list=1)
    CPU2: clear both flags (store 0)
    CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits

To avoid this class of races, convert these flags to separate bool
fields.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-23230?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23230?

Apply the vendor's patch.

## Is CVE-2026-23230 being exploited?

There is no known exploitation of CVE-2026-23230 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23230 and fix it if it is affected.

What it is: CVE-2026-23230 is a high-severity vulnerability in Linux kernel, published on 18 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-23230 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-23230/ (Markdown: https://insights.sbomify.com/CVE-2026-23230/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23230
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23230
- OSV: https://osv.dev/vulnerability/CVE-2026-23230

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23230/
Summaries are generated and may contain mistakes; the official description above is the record.