# CVE-2026-98422: wifi: mac80211: reset the AP_VLAN tailroom counter on ifdown

> A logic error in the Linux kernel Wi-Fi subsystem allows a local attacker to trigger a kernel warning and potential denial of service by repeatedly toggling AP VLAN interfaces.

- **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:** 14 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-108110, BELL-CVE-2026-98422, DEBIAN-CVE-2026-98422, GHSA-7fq6-p34m-gv65, UBUNTU-CVE-2026-98422

## What is CVE-2026-98422?

CVE-2026-98422 is a denial of service vulnerability in Linux, published on 14 Oct 2026. 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: mac80211: reset the AP_VLAN tailroom counter on ifdown

On ifup, AP_VLAN interfaces get crypto_tx_tailroom_needed_cnt from
the AP interface, but it's never decremented again unless the AP is
also brought down. Thus, bringing the same AP_VLAN up again will
increment the counter again and eventually hit the sanity check:

  WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt !=
               master->crypto_tx_tailroom_needed_cnt);

Reset it on ifdown to avoid that.

## Which versions are affected by CVE-2026-98422?


## How do I fix CVE-2026-98422?

Apply the vendor's patch.

## Is CVE-2026-98422 being exploited?

There is no known exploitation of CVE-2026-98422 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98422 and fix it if it is affected.

What it is: CVE-2026-98422 is a denial of service vulnerability in Linux, published on 14 Oct 2026. 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-2026-98422 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-2026-98422/ (Markdown: https://insights.sbomify.com/CVE-2026-98422/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98422
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98422
- OSV: https://osv.dev/vulnerability/CVE-2026-98422

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98422/
Summaries are generated and may contain mistakes; the official description above is the record.