# CVE-2026-64597: smb: client: fix double-free in SMB2_close() replay

> A double-free vulnerability in the Linux kernel SMB client allows attackers to cause denial of service or potentially execute code via crafted SMB2 close operations.

- **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:** 6 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-64597, DEBIAN-CVE-2026-64597, GHSA-4vgx-hp6g-jmm8, UBUNTU-CVE-2026-64597

## What is CVE-2026-64597?

CVE-2026-64597 is a critical use after free vulnerability in Linux, published on 6 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 double-free in SMB2_close() replay

A response-bearing attempt can return a replayable error and free its
response buffer. If SMB2_close_init() fails before the next send, cleanup
retains the previous buffer type and frees that response again.

Reset response bookkeeping before each attempt to prevent the stale free.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2026-64597?


## How do I fix CVE-2026-64597?

Apply the vendor's patch.

## Is CVE-2026-64597 being exploited?

There is no known exploitation of CVE-2026-64597 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64597 and fix it if it is affected.

What it is: CVE-2026-64597 is a critical use after free vulnerability in Linux, published on 6 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-2026-64597 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-2026-64597/ (Markdown: https://insights.sbomify.com/CVE-2026-64597/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64597
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64597
- OSV: https://osv.dev/vulnerability/CVE-2026-64597

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64597/
Summaries are generated and may contain mistakes; the official description above is the record.