---
id: CVE-2026-74499
title: 'ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()'
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()\n\nsnd_usbmidi_akai_output() computes its fill-loop bound\n\n\tbuf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - …"
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    78dfdeb8d2065524ed5928d6470bf3d3244d1009
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    00cc659a42ac4e94ec880fae2c9bf22fce69c2e8
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    ce949d66607cfb000b8d8d84f80f35a886e72683
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    29a4c29943631301e85f5e9d10f25741bd78e7ba
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    9b22a5c8310b0d55d04f5f0159b913a2fb8b444f
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    b5305a0d0bb8e90a6fc9f88270d5f6c9b8c40081
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    2b7a0f330dd90dd1a7657cec0db019ee1efa4372
  - >-
    Linux >= 4434ade8c9334a3ab975d8993de456f06841899e <
    0970274613fb463d376211450cab066d34ebfe6a
  - Linux 2.6.35
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:58:49.686471Z'
published: '2026-08-15'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T17:05:47.592Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74499'
references:
  - url: 'https://git.kernel.org/stable/c/78dfdeb8d2065524ed5928d6470bf3d3244d1009'
  - url: 'https://git.kernel.org/stable/c/00cc659a42ac4e94ec880fae2c9bf22fce69c2e8'
  - url: 'https://git.kernel.org/stable/c/ce949d66607cfb000b8d8d84f80f35a886e72683'
  - url: 'https://git.kernel.org/stable/c/29a4c29943631301e85f5e9d10f25741bd78e7ba'
  - url: 'https://git.kernel.org/stable/c/9b22a5c8310b0d55d04f5f0159b913a2fb8b444f'
  - url: 'https://git.kernel.org/stable/c/b5305a0d0bb8e90a6fc9f88270d5f6c9b8c40081'
  - url: 'https://git.kernel.org/stable/c/2b7a0f330dd90dd1a7657cec0db019ee1efa4372'
  - url: 'https://git.kernel.org/stable/c/0970274613fb463d376211450cab066d34ebfe6a'
tags:
  - cve.org
epss: 0.00177
epssPercentile: 0.07265
ingestedAt: '2026-11-06T18:00:12.551Z'
---

## Overview

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

ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()

snd_usbmidi_akai_output() computes its fill-loop bound

	buf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - 1;

as a signed int, so a small device-advertised bulk-OUT max_transfer
makes buf_end negative.  The loop guard then compares the u32
urb->transfer_buffer_length against that negative int: the usual
arithmetic conversion turns buf_end into a large unsigned value, so the
guard stays true and each iteration keeps appending SysEx framing and
payload bytes past the end of the URB transfer buffer, which is only
max_transfer bytes long.

A USB device that advertises a tiny bulk-OUT endpoint can therefore
trigger an attacker-length- and content-controlled heap out-of-bounds
write when a process writes to the created /dev/snd/midiC*D* node.

Return early when there is no room for even one SysEx, so the loop is
never entered with a bound that would wrap.  The loop is the last
statement of the function, so bailing out is equivalent to it not
running.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

## Affected

- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 78dfdeb8d2065524ed5928d6470bf3d3244d1009`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 00cc659a42ac4e94ec880fae2c9bf22fce69c2e8`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < ce949d66607cfb000b8d8d84f80f35a886e72683`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 29a4c29943631301e85f5e9d10f25741bd78e7ba`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 9b22a5c8310b0d55d04f5f0159b913a2fb8b444f`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < b5305a0d0bb8e90a6fc9f88270d5f6c9b8c40081`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 2b7a0f330dd90dd1a7657cec0db019ee1efa4372`
- `Linux >= 4434ade8c9334a3ab975d8993de456f06841899e < 0970274613fb463d376211450cab066d34ebfe6a`
- `Linux 2.6.35`

## Remediation

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