# CVE-2025-38665: can: netlink: can_changelink(): fix NULL pointer deref of struct can_priv::do_set_mode

> A NULL pointer dereference in the Linux kernel CAN subsystem allows local attackers to cause a denial of service by triggering a specific device restart sequence.

- **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:** 22 Aug 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-66587, AZL-73638, BELL-CVE-2025-38665, DEBIAN-CVE-2025-38665, GHSA-33pj-gwj2-3g99, ROOT-OS-DEBIAN-11-CVE-2025-38665, ROOT-OS-DEBIAN-12-CVE-2025-38665, ROOT-OS-DEBIAN-13-CVE-2025-38665, ROOT-OS-UBUNTU-2204-CVE-2025-38665, ROOT-OS-UBUNTU-2404-CVE-2025-38665, UBUNTU-CVE-2025-38665

## What is CVE-2025-38665?

CVE-2025-38665 is a medium-severity vulnerability in Debian Debian Linux, published on 22 Aug 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:

can: netlink: can_changelink(): fix NULL pointer deref of struct can_priv::do_set_mode

Andrei Lalaev reported a NULL pointer deref when a CAN device is
restarted from Bus Off and the driver does not implement the struct
can_priv::do_set_mode callback.

There are 2 code path that call struct can_priv::do_set_mode:
- directly by a manual restart from the user space, via
  can_changelink()
- delayed automatic restart after bus off (deactivated by default)

To prevent the NULL pointer deference, refuse a manual restart or
configure the automatic restart delay in can_changelink() and report
the error via extack to user space.

As an additional safety measure let can_restart() return an error if
can_priv::do_set_mode is not set instead of dereferencing it
unchecked.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-38665?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38665?

Apply the vendor's patch.

## Is CVE-2025-38665 being exploited?

There is no known exploitation of CVE-2025-38665 in the wild and no public exploit code.

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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-2025-38665 and fix it if it is affected.

What it is: CVE-2025-38665 is a medium-severity vulnerability in Debian Debian Linux, published on 22 Aug 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-2025-38665 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-2025-38665/ (Markdown: https://insights.sbomify.com/CVE-2025-38665/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38665
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38665
- OSV: https://osv.dev/vulnerability/CVE-2025-38665

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38665/
Summaries are generated and may contain mistakes; the official description above is the record.