---
id: CVE-2026-64032
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bridge: mcast: Fix a possible use-after-free when removing a bridge port

  When per-VLAN multicast snooping is enabled, the bridge iterates over
  all the bridge ports, di…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bridge: mcast: Fix a possible use-after-free when removing a bridge port

  When per-VLAN multicast snooping is enabled, the bridge iterates over
  all the bridge ports, di…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.15.186, < 5.15.209'
  - 'linux_kernel >= 6.1.142, < 6.1.175'
  - 'linux_kernel >= 6.6.95, < 6.6.142'
  - 'linux_kernel >= 6.12.35, < 6.12.92'
  - 'linux_kernel >= 6.15.4, < 6.18.34'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T15:32:51.113'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64032'
references:
  - url: 'https://git.kernel.org/stable/c/1900ca8acb92fbea8bf9abef9927c7fed03db7fc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4df78ff02629c7729168f0696a7a2123c389818d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7213256c91ed778a0997c2029c152b18dc50e4fd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9224862d597d0eed0a34bbb27343f703fc4113f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ddefd1b8e5eb58933a697ab38334f0fd82e7fb8b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ebe5561154c823b323bd06e350b55e0b8604d851'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ed3b69e60385a03df11c6d12e5d7bdf0f4a11b70'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00171
epssPercentile: 0.0599
ingestedAt: '2026-10-13T15:33:40.028Z'
---

## Overview

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

bridge: mcast: Fix a possible use-after-free when removing a bridge port

When per-VLAN multicast snooping is enabled, the bridge iterates over
all the bridge ports, disables the per-port multicast context on each
port and enables the per-{port, VLAN} multicast contexts instead. The
reverse happens when per-VLAN multicast snooping is disabled.

When global multicast snooping is enabled, the bridge iterates over all
the bridge ports and enables the per-port multicast context on each
port. The reverse happens when multicast snooping is disabled.

The above scheme can result in a situation where both types of contexts
(per-port and per-{port, VLAN}) are enabled on a single bridge port:

 # ip link add name br1 up type bridge mcast_snooping 1 mcast_querier 1 vlan_filtering 1
 # ip link add name dummy1 up master br1 type dummy
 # ip link set dev br1 type bridge mcast_vlan_snooping 1
 # ip link set dev br1 type bridge mcast_snooping 0
 # ip link set dev br1 type bridge mcast_snooping 1

This is not intended and it is a problem since the commit cited below.
Prior to this commit, when removing a bridge port,
br_multicast_disable_port() would disable the per-port multicast context
and the per-{port, VLAN} multicast contexts would get disabled when
flushing VLANs.

After this commit, br_multicast_disable_port() only disables the
per-port multicast context if per-VLAN multicast snooping is disabled.
If both types of contexts were enabled on the port when it was removed,
the per-port multicast context would remain enabled when freeing the
bridge port, leading to a use-after-free [1].

Fix by preventing the bridge from enabling / disabling the per-port
multicast contexts when toggling global multicast snooping if per-VLAN
multicast snooping is enabled.

[1]
ODEBUG: free active (active state 0) object: ffff88810f8bda78 object type: timer_list hint: br_ip6_multicast_port_query_expired (net/bridge/br_multicast.c:1927)
WARNING: lib/debugobjects.c:629 at debug_print_object+0x1b1/0x3e0, CPU#5: swapper/5/0
[...]
Call Trace:
<IRQ>
__debug_check_no_obj_freed (lib/debugobjects.c:1116)
kfree (mm/slub.c:2620 mm/slub.c:6250 mm/slub.c:6565)
kobject_cleanup (lib/kobject.c:689)
rcu_do_batch (kernel/rcu/tree.c:2617)
rcu_core (kernel/rcu/tree.c:2869)
handle_softirqs (kernel/softirq.c:622)
__irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735)
irq_exit_rcu (kernel/softirq.c:752)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1061 (discriminator 47) arch/x86/kernel/apic/apic.c:1061 (discriminator 47))
</IRQ>

## Affected

- `linux_kernel >= 5.15.186, < 5.15.209`
- `linux_kernel >= 6.1.142, < 6.1.175`
- `linux_kernel >= 6.6.95, < 6.6.142`
- `linux_kernel >= 6.12.35, < 6.12.92`
- `linux_kernel >= 6.15.4, < 6.18.34`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`