---
id: CVE-2026-43083
title: 'net: ioam6: fix OOB and missing lock'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: ioam6: fix OOB and missing lock

  When trace->type.bit6 is set:

      if (trace->type.bit6) {
          ...
          queue = skb_get_tx_queue(dev, skb);
          qdisc =…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 <
    6d1d9ed9b409e0662241e3d245d574a18f643494
  - >-
    Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 <
    95a1334748c95dd15546056280ade0c4b8dd7b78
  - >-
    Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 <
    b30b1675aa2bcf0491fd3830b051df4e08a7c8ca
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T15:14:26.779582Z'
published: '2026-05-06'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:20:31.904Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43083'
references:
  - url: 'https://git.kernel.org/stable/c/6d1d9ed9b409e0662241e3d245d574a18f643494'
  - url: 'https://git.kernel.org/stable/c/95a1334748c95dd15546056280ade0c4b8dd7b78'
  - url: 'https://git.kernel.org/stable/c/b30b1675aa2bcf0491fd3830b051df4e08a7c8ca'
tags:
  - cve.org
epss: 0.00632
epssPercentile: 0.49221
ingestedAt: '2026-10-16T17:24:46.681Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

net: ioam6: fix OOB and missing lock

When trace->type.bit6 is set:

    if (trace->type.bit6) {
        ...
        queue = skb_get_tx_queue(dev, skb);
        qdisc = rcu_dereference(queue->qdisc);

This code can lead to an out-of-bounds access of the dev->_tx[] array
when is_input is true. In such a case, the packet is on the RX path and
skb->queue_mapping contains the RX queue index of the ingress device. If
the ingress device has more RX queues than the egress device (dev) has
TX queues, skb_get_queue_mapping(skb) will exceed dev->num_tx_queues.
Add a check to avoid this situation since skb_get_tx_queue() does not
clamp the index. This issue has also revealed that per queue visibility
cannot be accurate and will be replaced later as a new feature.

While at it, add missing lock around qdisc_qstats_qlen_backlog(). The
function __ioam6_fill_trace_data() is called from both softirq and
process contexts, hence the use of spin_lock_bh() here.

## Affected

- `Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 < 6d1d9ed9b409e0662241e3d245d574a18f643494`
- `Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 < 95a1334748c95dd15546056280ade0c4b8dd7b78`
- `Linux >= b63c5478e9cb1d1504eb02d9dac827ad24612b32 < b30b1675aa2bcf0491fd3830b051df4e08a7c8ca`
- `Linux 5.17`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.