---
id: CVE-2026-74480
title: 'net: bridge: stop fast-leave after deleting a port group'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: bridge: stop fast-leave after deleting a port group

  br_multicast_leave_group() iterates mp->ports with pp = &p->next in
  its fast-leave path. After br_multicast_de…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    d6c32e2e25a9a06ba021030e26b6d602a277eb72
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    482bcb85139addb4e8ac8ed10baeda3e0aad4031
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    1a109cc9890d017c41d77e6c82da739579c49f0b
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    159ad90cb929c033308bb39a2c5f8fbf393b77aa
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    4695430e8132420bf8de94da3eb36a6cf35fde6b
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    0309ebbc570000ea0df11c06b69798e5860c5f6f
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4
  - >-
    Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 <
    a39789f211b8a4125f0c70e05b30cf715f4f187d
  - Linux 4.11
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:57:40.918598Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:48.808Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74480'
references:
  - url: 'https://git.kernel.org/stable/c/d6c32e2e25a9a06ba021030e26b6d602a277eb72'
  - url: 'https://git.kernel.org/stable/c/482bcb85139addb4e8ac8ed10baeda3e0aad4031'
  - url: 'https://git.kernel.org/stable/c/1a109cc9890d017c41d77e6c82da739579c49f0b'
  - url: 'https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa'
  - url: 'https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b'
  - url: 'https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f'
  - url: 'https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4'
  - url: 'https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d'
tags:
  - cve.org
epss: 0.00579
epssPercentile: 0.4649
ingestedAt: '2026-10-16T19:46:24.355Z'
---

## Overview

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

net: bridge: stop fast-leave after deleting a port group

br_multicast_leave_group() iterates mp->ports with pp = &p->next in
its fast-leave path. After br_multicast_del_pg() removes p,
continuing the loop advances pp through the deleted entry.

If multicast-to-unicast was enabled, the bridge can hold multiple port
groups for the same port and group with different source MAC
addresses. Once multicast-to-unicast is disabled,
br_port_group_equal() matches those entries by port only. A fast leave
can then delete one entry and continue from its stale next pointer,
leaving mp->ports pointing at a deleted port group.

Fast leave only needs to remove one matching port group. Break after
br_multicast_del_pg() so the loop stops before dereferencing the
removed entry.

## Affected

- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < d6c32e2e25a9a06ba021030e26b6d602a277eb72`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 482bcb85139addb4e8ac8ed10baeda3e0aad4031`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 1a109cc9890d017c41d77e6c82da739579c49f0b`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 159ad90cb929c033308bb39a2c5f8fbf393b77aa`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 4695430e8132420bf8de94da3eb36a6cf35fde6b`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 0309ebbc570000ea0df11c06b69798e5860c5f6f`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < 4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4`
- `Linux >= 6db6f0eae6052b70885562e1733896647ec1d807 < a39789f211b8a4125f0c70e05b30cf715f4f187d`
- `Linux 4.11`

## Remediation

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