# CVE-2021-47225: mac80211: fix deadlock in AP/VLAN handling

> A deadlock in the Linux kernel mac80211 subsystem can cause a denial of service when closing AP interfaces with active VLANs.

- **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:** No
- **Published:** 21 May 2024
- **Updated:** 11 May 2026
- **Also known as:** GHSA-mpm3-wjp6-8g7x, UBUNTU-CVE-2021-47225

## What is CVE-2021-47225?

CVE-2021-47225 is a medium-severity vulnerability in Linux kernel, published on 21 May 2024. 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:

mac80211: fix deadlock in AP/VLAN handling

Syzbot reports that when you have AP_VLAN interfaces that are up
and close the AP interface they belong to, we get a deadlock. No
surprise - since we dev_close() them with the wiphy mutex held,
which goes back into the netdev notifier in cfg80211 and tries to
acquire the wiphy mutex there.

To fix this, we need to do two things:
 1) prevent changing iftype while AP_VLANs are up, we can't
    easily fix this case since cfg80211 already calls us with
    the wiphy mutex held, but change_interface() is relatively
    rare in drivers anyway, so changing iftype isn't used much
    (and userspace has to fall back to down/change/up anyway)
 2) pull the dev_close() loop over VLANs out of the wiphy mutex
    section in the normal stop case

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2021-47225?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47225?

No fix has been published for CVE-2021-47225 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47225 being exploited?

There is no known exploitation of CVE-2021-47225 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-2021-47225 and fix it if it is affected.

What it is: CVE-2021-47225 is a medium-severity vulnerability in Linux kernel, published on 21 May 2024. 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-2021-47225 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-2021-47225/ (Markdown: https://insights.sbomify.com/CVE-2021-47225/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47225
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47225
- OSV: https://osv.dev/vulnerability/CVE-2021-47225

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47225/
Summaries are generated and may contain mistakes; the official description above is the record.