# CVE-2025-40066: wifi: mt76: mt7996: Check phy before init msta_link in mt7996_mac_sta_add_links()

> A missing null check in the mt7996 WiFi driver can cause a kernel crash, leading to denial of service for local or adjacent attackers.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Oct 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-40066, DEBIAN-CVE-2025-40066, GHSA-8r3f-48gc-phmq, UBUNTU-CVE-2025-40066

## What is CVE-2025-40066?

CVE-2025-40066 is a vulnerability in Linux, published on 28 Oct 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:

wifi: mt76: mt7996: Check phy before init msta_link in mt7996_mac_sta_add_links()

In order to avoid a possible NULL pointer dereference in
mt7996_mac_sta_init_link routine, move the phy pointer check before
running mt7996_mac_sta_init_link() in mt7996_mac_sta_add_links routine.

## Which versions are affected by CVE-2025-40066?


## How do I fix CVE-2025-40066?

Apply the vendor's patch.

## Is CVE-2025-40066 being exploited?

There is no known exploitation of CVE-2025-40066 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40066 and fix it if it is affected.

What it is: CVE-2025-40066 is a vulnerability in Linux, published on 28 Oct 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-2025-40066 in the wild and no public exploit code.

Affected product: 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-2025-40066/ (Markdown: https://insights.sbomify.com/CVE-2025-40066/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40066
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40066
- OSV: https://osv.dev/vulnerability/CVE-2025-40066

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40066/
Summaries are generated and may contain mistakes; the official description above is the record.