---
id: CVE-2026-74278
title: 'ALSA: seq: Fix kernel heap address leak in bounce_error_event()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: seq: Fix kernel heap address leak in bounce_error_event()

  The comment above bounce_error_event() documents that user clients
  should receive SNDRV_SEQ_EVENT_BOUNC…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    eae296065ede41a24040e6a7c909ec970f78b4eb
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    93d260ce43a81df579c98bee92b91316df9c1c57
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    dae23c545eb5a2be3b27a82fd0f611894fb8ab69
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    0527a56cb327021cb73167cfddf0e49efa043500
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    efc86691e4d8083d9e380ea95042c2cf679f65fd
  - Linux 2.6.12
published: '2026-08-15'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:45:16.258Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74278'
references:
  - url: 'https://git.kernel.org/stable/c/eae296065ede41a24040e6a7c909ec970f78b4eb'
  - url: 'https://git.kernel.org/stable/c/93d260ce43a81df579c98bee92b91316df9c1c57'
  - url: 'https://git.kernel.org/stable/c/dae23c545eb5a2be3b27a82fd0f611894fb8ab69'
  - url: 'https://git.kernel.org/stable/c/0527a56cb327021cb73167cfddf0e49efa043500'
  - url: 'https://git.kernel.org/stable/c/efc86691e4d8083d9e380ea95042c2cf679f65fd'
tags:
  - cve.org
epss: 0.00168
epssPercentile: 0.05735
ingestedAt: '2026-10-21T12:48:53.585Z'
---

## Overview

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

ALSA: seq: Fix kernel heap address leak in bounce_error_event()

The comment above bounce_error_event() documents that user clients
should receive SNDRV_SEQ_EVENT_BOUNCE with the original event embedded
as variable-length data, while kernel clients should receive
SNDRV_SEQ_EVENT_KERNEL_ERROR with a quoted kernel pointer.

However, the implementation unconditionally uses
SNDRV_SEQ_EVENT_KERNEL_ERROR with data.quote.event set to the raw
struct snd_seq_event pointer for all clients.  When a bounce error
event is delivered to a USER_CLIENT via snd_seq_read(), the kernel
heap address in data.quote.event is exposed to userspace through
copy_to_user() in the fixed-length branch.

This is a distinct leak path from the one addressed by commit
705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read"),
which sanitizes data.ext.ptr in the variable-length branch of
snd_seq_read().  The bounce_error_event() leak uses fixed-length
events that take the else branch where no sanitization occurs.

Differentiate the bounce event by client type.  For USER_CLIENT,
send SNDRV_SEQ_EVENT_BOUNCE with SNDRV_SEQ_EVENT_LENGTH_VARIABLE
and data.ext pointing to the original event.  The variable-length
path in snd_seq_event_dup() copies the event data into chained
cells, and snd_seq_expand_var_event() copies only the content --
never the pointer -- to userspace.  For KERNEL_CLIENT, keep the
existing SNDRV_SEQ_EVENT_KERNEL_ERROR behavior with the quoted
pointer.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < eae296065ede41a24040e6a7c909ec970f78b4eb`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 93d260ce43a81df579c98bee92b91316df9c1c57`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dae23c545eb5a2be3b27a82fd0f611894fb8ab69`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 0527a56cb327021cb73167cfddf0e49efa043500`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < efc86691e4d8083d9e380ea95042c2cf679f65fd`
- `Linux 2.6.12`

## Remediation

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