---
id: CVE-2026-74339
title: 'ALSA: seq: Clear variable event pointer on read'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: seq: Clear variable event pointer on read

  snd_seq_read() copies a queued variable-length event header to userspace
  before expanding the payload. Queued variable-…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    8a631e1aaa1ebbc9de916927fa01707244e18291
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    14fe4f75fd5309d6b75f8e840ada88912b374207
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    f29243c211928114f8b906e0a3fee77c236f14c8
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    e0c3edd86414534cfd179fefe45b38c29c01ae7a
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6b52211eba213c461f68922708a99d8190c1fcd5
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    74ac1ce1f4afdb3b80b6742fa28fb86c8c51d31b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c2ac9287e89916da684c2a548798351e63eb59ee
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    705dd6dcbc0ea87351c660c1a6443f85f1001c76
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:56:18.435565Z'
published: '2026-08-15'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T17:05:44.354Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74339'
references:
  - url: 'https://git.kernel.org/stable/c/8a631e1aaa1ebbc9de916927fa01707244e18291'
  - url: 'https://git.kernel.org/stable/c/14fe4f75fd5309d6b75f8e840ada88912b374207'
  - url: 'https://git.kernel.org/stable/c/f29243c211928114f8b906e0a3fee77c236f14c8'
  - url: 'https://git.kernel.org/stable/c/e0c3edd86414534cfd179fefe45b38c29c01ae7a'
  - url: 'https://git.kernel.org/stable/c/6b52211eba213c461f68922708a99d8190c1fcd5'
  - url: 'https://git.kernel.org/stable/c/74ac1ce1f4afdb3b80b6742fa28fb86c8c51d31b'
  - url: 'https://git.kernel.org/stable/c/c2ac9287e89916da684c2a548798351e63eb59ee'
  - url: 'https://git.kernel.org/stable/c/705dd6dcbc0ea87351c660c1a6443f85f1001c76'
tags:
  - cve.org
epss: 0.0022
epssPercentile: 0.12545
ingestedAt: '2026-11-05T15:02:32.537Z'
---

## Overview

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

ALSA: seq: Clear variable event pointer on read

snd_seq_read() copies a queued variable-length event header to userspace
before expanding the payload. Queued variable-length events use
SNDRV_SEQ_EXT_CHAINED internally, and data.ext.ptr points at the first
extension cell.

The read side strips SNDRV_SEQ_EXT_* bits from data.ext.len before the
copy, but it leaves data.ext.ptr untouched. A userspace sequencer client
can therefore write a direct variable event to itself and read back the
extension-cell kernel address from the returned header.

Clear the temporary header pointer before copy_to_user(). The original
queued event remains unchanged and is still passed to
snd_seq_expand_var_event(), so payload expansion keeps using the
internal chain.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8a631e1aaa1ebbc9de916927fa01707244e18291`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 14fe4f75fd5309d6b75f8e840ada88912b374207`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f29243c211928114f8b906e0a3fee77c236f14c8`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e0c3edd86414534cfd179fefe45b38c29c01ae7a`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6b52211eba213c461f68922708a99d8190c1fcd5`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 74ac1ce1f4afdb3b80b6742fa28fb86c8c51d31b`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c2ac9287e89916da684c2a548798351e63eb59ee`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 705dd6dcbc0ea87351c660c1a6443f85f1001c76`
- `Linux 2.6.12`

## Remediation

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