# CVE-2025-39875: igb: Fix NULL pointer dereference in ethtool loopback test

> A NULL pointer dereference in the Linux kernel igb driver during ethtool loopback tests can cause a system crash.

- **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:** 23 Sep 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-39875, DEBIAN-CVE-2025-39875, GHSA-h2wv-j9q6-hqmc, UBUNTU-CVE-2025-39875

## What is CVE-2025-39875?

CVE-2025-39875 is a medium-severity vulnerability in Linux kernel, published on 23 Sep 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:

igb: Fix NULL pointer dereference in ethtool loopback test

The igb driver currently causes a NULL pointer dereference when executing
the ethtool loopback test. This occurs because there is no associated
q_vector for the test ring when it is set up, as interrupts are typically
not added to the test rings.

Since commit 5ef44b3cb43b removed the napi_id assignment in
__xdp_rxq_info_reg(), there is no longer a need to pass a napi_id to it.
Therefore, simply use 0 as the last parameter.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-39875?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39875?

Apply the vendor's patch.

## Is CVE-2025-39875 being exploited?

There is no known exploitation of CVE-2025-39875 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-39875 and fix it if it is affected.

What it is: CVE-2025-39875 is a medium-severity vulnerability in Linux kernel, published on 23 Sep 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-2025-39875 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-39875/ (Markdown: https://insights.sbomify.com/CVE-2025-39875/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39875
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39875
- OSV: https://osv.dev/vulnerability/CVE-2025-39875

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39875/
Summaries are generated and may contain mistakes; the official description above is the record.