# CVE-2026-98261: cifs: Fix server use-after-free in cifs_chan_skip_or_disable()

> A use-after-free in the Linux kernel CIFS module allows attackers to cause denial of service or execute arbitrary code via secondary channel handling.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106014, BELL-CVE-2026-98261, DEBIAN-CVE-2026-98261, GHSA-mfc9-mfpp-wwcf, UBUNTU-CVE-2026-98261

## What is CVE-2026-98261?

CVE-2026-98261 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, with no action from the victim.

### Official description

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

cifs: Fix server use-after-free in cifs_chan_skip_or_disable()

When a secondary channel is no longer supported by the server,
cifs_chan_skip_or_disable() drops the channel reference with
cifs_put_tcp_session() and then continues to use the server pointer by
calling cifs_signal_cifsd_for_reconnect() on it and reading its
primary_server pointer. cifs_put_tcp_session() can drop the last
reference of the channel and tear it down, so both the channel and the
primary server (whose reference is also dropped by
cifs_put_tcp_session()) can be freed before they are signaled for
reconnect.

Signal the channel and the primary server and capture the primary
server pointer before dropping the channel reference with
cifs_put_tcp_session().

## Which versions are affected by CVE-2026-98261?


## How do I fix CVE-2026-98261?

Apply the vendor's patch.

## Is CVE-2026-98261 being exploited?

There is no known exploitation of CVE-2026-98261 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98261 and fix it if it is affected.

What it is: CVE-2026-98261 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, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98261 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-2026-98261/ (Markdown: https://insights.sbomify.com/CVE-2026-98261/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98261
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98261
- OSV: https://osv.dev/vulnerability/CVE-2026-98261

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98261/
Summaries are generated and may contain mistakes; the official description above is the record.