# CVE-2026-31394: mac80211: fix crash in ieee80211_chan_bw_change for AP_VLAN stations

> A NULL pointer dereference in the Linux kernel mac80211 subsystem allows attackers to cause a system crash via crafted Wi-Fi channel switch announcements.

- **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:** Yes
- **Published:** 3 Apr 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-31394, DEBIAN-CVE-2026-31394, GHSA-96f2-8m7p-q7j4, ROOT-OS-DEBIAN-11-CVE-2026-31394, ROOT-OS-DEBIAN-12-CVE-2026-31394, ROOT-OS-DEBIAN-13-CVE-2026-31394, ROOT-OS-UBUNTU-2204-CVE-2026-31394, ROOT-OS-UBUNTU-2404-CVE-2026-31394, UBUNTU-CVE-2026-31394

## What is CVE-2026-31394?

CVE-2026-31394 is a medium-severity vulnerability in Linux kernel, published on 3 Apr 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:

mac80211: fix crash in ieee80211_chan_bw_change for AP_VLAN stations

ieee80211_chan_bw_change() iterates all stations and accesses
link->reserved.oper via sta->sdata->link[link_id]. For stations on
AP_VLAN interfaces (e.g. 4addr WDS clients), sta->sdata points to
the VLAN sdata, whose link never participates in chanctx reservations.
This leaves link->reserved.oper zero-initialized with chan == NULL,
causing a NULL pointer dereference in __ieee80211_sta_cap_rx_bw()
when accessing chandef->chan->band during CSA.

Resolve the VLAN sdata to its parent AP sdata using get_bss_sdata()
before accessing link data.

[also change sta->sdata in ARRAY_SIZE even if it doesn't matter]

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31394?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31394?

Apply the vendor's patch.

## Is CVE-2026-31394 being exploited?

There is no known exploitation of CVE-2026-31394 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-2026-31394 and fix it if it is affected.

What it is: CVE-2026-31394 is a medium-severity vulnerability in Linux kernel, published on 3 Apr 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-2026-31394 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-2026-31394/ (Markdown: https://insights.sbomify.com/CVE-2026-31394/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31394
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31394
- OSV: https://osv.dev/vulnerability/CVE-2026-31394

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31394/
Summaries are generated and may contain mistakes; the official description above is the record.