---
id: CVE-2026-31394
title: |-
  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->…
summary: |-
  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->…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.11, < 6.12.78'
  - 'linux_kernel >= 6.13, < 6.18.20'
  - 'linux_kernel >= 6.19, < 6.19.10'
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.10
published: '2026-04-03'
updated: '2026-07-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31394'
references:
  - url: 'https://git.kernel.org/stable/c/3c6629e859a2211a1fbb4868f915413f80001ca5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5a86d4e920d9783a198e39cf53f0e410fba5fbd6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/65c25b588994dd422fea73fa322de56e1ae4a33b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/672e5229e1ecfc2a3509b53adcb914d8b024a853'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00114
epssPercentile: 0.01663
ingestedAt: '2026-07-25T22:05:04.128Z'
---

## Overview

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]

## Affected

- `linux_kernel >= 6.11, < 6.12.78`
- `linux_kernel >= 6.13, < 6.18.20`
- `linux_kernel >= 6.19, < 6.19.10`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.10`