# CVE-2025-9640: Samba: vfs_streams_xattr uninitialized memory write possible

> An authenticated user can read residual memory content via uninitialized heap writes in Samba's vfs_streams_xattr module, leading to information disclosure.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Oct 2025
- **Updated:** 1 Sep 2026
- **Also known as:** ALPINE-CVE-2025-9640, AZL-68817, AZL-68936, DEBIAN-CVE-2025-9640, DLA-4384-1, ECHO-bc79-1dde-0065, GHSA-w497-wqwx-v847, UBUNTU-CVE-2025-9640

## What is CVE-2025-9640?

CVE-2025-9640 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 15 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in Samba, in the vfs_streams_xattr module, where uninitialized heap memory could be written into alternate data streams. This allows an authenticated user to read residual memory content that may include sensitive data, resulting in an information disclosure vulnerability.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2025-9640?


## How do I fix CVE-2025-9640?

Apply the vendor's patch.

## Is CVE-2025-9640 being exploited?

There is no known exploitation of CVE-2025-9640 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-9640 and fix it if it is affected.

What it is: CVE-2025-9640 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 15 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-9640 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2025-9640/ (Markdown: https://insights.sbomify.com/CVE-2025-9640/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-9640
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-9640
- OSV: https://osv.dev/vulnerability/CVE-2025-9640

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-9640/
Summaries are generated and may contain mistakes; the official description above is the record.