# CVE-2026-98681: smb: client: split cifsFileInfo bitfields to avoid shared-byte RMW races

> Concurrent updates to SMB client flags can corrupt state due to race conditions, potentially causing data corruption or crashes.

- **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:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-109164, BELL-CVE-2026-98681, DEBIAN-CVE-2026-98681, GHSA-f6j4-gqwr-mpr2, UBUNTU-CVE-2026-98681

## What is CVE-2026-98681?

CVE-2026-98681 is a vulnerability in Linux, published on 18 Oct 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: split cifsFileInfo bitfields to avoid shared-byte RMW races

The invalidHandle, swapfile, oplock_break_cancelled, offload,
and status_file_deleted fields are stored in the same bitfield byte
in struct cifsFileInfo, but are updated in different code paths that
may run simultaneously, and are protected by different locks.  Since
bitfield assignments generate byte-level read-modify-write operations,
a modification to one flag can overwrite a concurrent modification to
another flag.

To avoid these races, convert these flags from a bitfield to
separate bool fields.

## Which versions are affected by CVE-2026-98681?


## How do I fix CVE-2026-98681?

Apply the vendor's patch.

## Is CVE-2026-98681 being exploited?

There is no known exploitation of CVE-2026-98681 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98681 and fix it if it is affected.

What it is: CVE-2026-98681 is a vulnerability in Linux, published on 18 Oct 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-2026-98681 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-2026-98681/ (Markdown: https://insights.sbomify.com/CVE-2026-98681/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98681
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98681
- OSV: https://osv.dev/vulnerability/CVE-2026-98681

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98681/
Summaries are generated and may contain mistakes; the official description above is the record.