# CVE-2026-74608: smb: client: Fix use-after-free in cifs_try_adding_channels()

> A use-after-free in the Linux kernel SMB client allows attackers to cause denial of service or execute arbitrary code via race conditions during channel creation.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/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:** 22 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97124, BELL-CVE-2026-74608, DEBIAN-CVE-2026-74608, GHSA-q727-xf93-53j5, UBUNTU-CVE-2026-74608

## What is CVE-2026-74608?

CVE-2026-74608 is a critical use after free vulnerability in Linux, published on 22 Aug 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 use-after-free in cifs_try_adding_channels()

cifs_try_adding_channels() takes a temporary reference to an interface
before dropping iface_lock. If cifs_ses_add_channel() fails, it drops
that reference and then increments iface->weight_fulfilled.

A concurrent interface list refresh can remove the list reference while
channel creation is in progress. In that case, the failure-path
kref_put() releases the last reference and frees iface. Updating
weight_fulfilled afterward then accesses freed memory.

Increment weight_fulfilled before dropping the temporary reference,
keeping iface alive for the final access.

## Which versions are affected by CVE-2026-74608?


## How do I fix CVE-2026-74608?

Apply the vendor's patch.

## Is CVE-2026-74608 being exploited?

There is no known exploitation of CVE-2026-74608 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74608 and fix it if it is affected.

What it is: CVE-2026-74608 is a critical use after free vulnerability in Linux, published on 22 Aug 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-2026-74608 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-2026-74608/ (Markdown: https://insights.sbomify.com/CVE-2026-74608/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74608
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74608
- OSV: https://osv.dev/vulnerability/CVE-2026-74608

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74608/
Summaries are generated and may contain mistakes; the official description above is the record.