# CVE-2025-38086: net: ch9200: fix uninitialised access during mii_nway_restart

> A local attacker can read uninitialized kernel memory via the ch9200 network driver due to missing error checks, potentially exposing sensitive data.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jun 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-64383, BELL-CVE-2025-38086, DEBIAN-CVE-2025-38086, GHSA-33v2-gr7f-4wmr, ROOT-OS-DEBIAN-11-CVE-2025-38086, ROOT-OS-DEBIAN-12-CVE-2025-38086, ROOT-OS-UBUNTU-2204-CVE-2025-38086, ROOT-OS-UBUNTU-2404-CVE-2025-38086, UBUNTU-CVE-2025-38086

## What is CVE-2025-38086?

CVE-2025-38086 is a medium-severity vulnerability in Debian Debian Linux, published on 28 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

net: ch9200: fix uninitialised access during mii_nway_restart

In mii_nway_restart() the code attempts to call
mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read()
utilises a local buffer called "buff", which is initialised
with control_read(). However "buff" is conditionally
initialised inside control_read():

        if (err == size) {
                memcpy(data, buf, size);
        }

If the condition of "err == size" is not met, then
"buff" remains uninitialised. Once this happens the
uninitialised "buff" is accessed and returned during
ch9200_mdio_read():

        return (buff[0] | buff[1] << 8);

The problem stems from the fact that ch9200_mdio_read()
ignores the return value of control_read(), leading to
uinit-access of "buff".

To fix this we should check the return value of
control_read() and return early on error.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2025-38086?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38086?

Apply the vendor's patch.

## Is CVE-2025-38086 being exploited?

There is no known exploitation of CVE-2025-38086 in the wild and no public exploit code.

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- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
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- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-38086 and fix it if it is affected.

What it is: CVE-2025-38086 is a medium-severity vulnerability in Debian Debian Linux, published on 28 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-38086 in the wild and no public exploit code.

Affected product: Debian Debian 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-2025-38086/ (Markdown: https://insights.sbomify.com/CVE-2025-38086/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38086
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38086
- OSV: https://osv.dev/vulnerability/CVE-2025-38086

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38086/
Summaries are generated and may contain mistakes; the official description above is the record.