# CVE-2026-98175: smb: client: cancel reconnect work in clean_demultiplex_info()

> A use-after-free in the Linux kernel SMB client allows attackers to cause denial of service or execute code when reconnect work is queued during cleanup.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106059, BELL-CVE-2026-98175, DEBIAN-CVE-2026-98175, GHSA-22vf-w84m-jw7w, UBUNTU-CVE-2026-98175

## What is CVE-2026-98175?

CVE-2026-98175 is a high-severity use after free vulnerability in Linux, published on 6 Oct 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: cancel reconnect work in clean_demultiplex_info()

clean_demultiplex_info() cancels server->echo delayed work but not
server->reconnect, which can cause a use-after-free when the
demultiplex thread exits while a reconnect work is still queued:

  cifs_demultiplex_thread()
    cifs_readv_from_socket()
      cifs_reconnect()
        __cifs_reconnect()
          cifs_queue_server_reconn()
            mod_delayed_work(cifsiod_wq, &server->reconnect, 0)
    clean_demultiplex_info()
      cancel_delayed_work_sync(&server->echo)   // echo canceled
                                                 // reconnect NOT canceled
      kfree_sensitive(server)                    // server freed

  ...later, on cifsiod_wq:

  smb2_reconnect_server()
    server->srv_count  // UAF read of freed server

Fix this by canceling server->reconnect delayed work in
clean_demultiplex_info() before the server is freed, the same way
cifs_put_tcp_session() already does.

## Which versions are affected by CVE-2026-98175?


## How do I fix CVE-2026-98175?

Apply the vendor's patch.

## Is CVE-2026-98175 being exploited?

There is no known exploitation of CVE-2026-98175 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98175 and fix it if it is affected.

What it is: CVE-2026-98175 is a high-severity use after free vulnerability in Linux, published on 6 Oct 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-2026-98175 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-2026-98175/ (Markdown: https://insights.sbomify.com/CVE-2026-98175/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98175
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98175
- OSV: https://osv.dev/vulnerability/CVE-2026-98175

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98175/
Summaries are generated and may contain mistakes; the official description above is the record.