---
id: CVE-2026-98265
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity

  data_ep_set_params() allocates each data URB for exactly u->packets
  isochronous frames, so urb->i…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity

  data_ep_set_params() allocates each data URB for exactly u->packets
  isochronous frames, so urb->i…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 32a1f64f8ff6e2c5391f5964baec697bce25b83c <
    ad279ba0dc1781229f5b52f58d38d56960400e06
  - >-
    Linux >= e949fd266cfa1dcca7caa3faa698578c4ffd26d6 <
    79c55a7b5d71cf2a6bbd4bd7698e1b10b70f813a
  - >-
    Linux >= cf044e44190234a41a788de1cdbb6c21f4a52e1e <
    ab77e3f453c5f2499c08d6e8e218501d25bab39e
  - >-
    Linux >= cf044e44190234a41a788de1cdbb6c21f4a52e1e <
    76a986c980bb502c7688d605ac7a67fd257a9a1b
  - Linux df75696e70c88b22ed1d8c9d515993a858c58fd0
  - Linux 3a74f6b46c01d9a816378cd83c327a59f61475ec
  - Linux c26bde6301f20d9aafbfb7c2459a88c6a6ec178f
  - Linux f6fbdf797e016fbf968dd54301026b182175985a
  - Linux >= 6.12.75 < 6.12.112
  - Linux >= 6.18.16 < 6.18.54
  - Linux >= 5.15.202 < 5.16
  - Linux >= 6.1.165 < 6.2
  - Linux >= 6.6.128 < 6.7
  - Linux >= 6.19.6 < 6.20
  - Linux 7.0
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T09:18:15.797'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98265'
references:
  - url: 'https://git.kernel.org/stable/c/76a986c980bb502c7688d605ac7a67fd257a9a1b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/79c55a7b5d71cf2a6bbd4bd7698e1b10b70f813a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ab77e3f453c5f2499c08d6e8e218501d25bab39e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ad279ba0dc1781229f5b52f58d38d56960400e06'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-06T08:50:17.426Z'
---

## Overview

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

ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity

data_ep_set_params() allocates each data URB for exactly u->packets
isochronous frames, so urb->iso_frame_desc[] has u->packets slots and
ctx->packets is the driver's only record of that limit. For an implicit
feedback sink, snd_usb_queue_pending_output_urbs() overwrites it with the
sync source's packet count, which is calculated independently from the
capture endpoint's parameters. When that count is larger,
prepare_playback_urb() and prepare_silent_urb() can write
iso_frame_desc[] past the allocation; their existing bounds limit payload
bytes, not the descriptor index.

The reproducer uses a high-speed UAC2 device declaring bInterval 1 for
implicit feedback capture (8 packets) and bInterval 4 for playback
(1 packet). On the first capture completion after the stream starts, it
accesses seven descriptors spanning 112 bytes beyond the one-packet URB:

  BUG: KASAN: slab-out-of-bounds in prepare_playback_urb (sound/usb/pcm.c:1560)
  Write of size 4 at addr ffff88801e696ad0 by task vhci_rx/178
   prepare_playback_urb (sound/usb/pcm.c:1560)
   prepare_outbound_urb (sound/usb/endpoint.c:340)
   snd_usb_queue_pending_output_urbs (sound/usb/endpoint.c:501)
   snd_complete_urb (sound/usb/endpoint.c:1834)
   __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657)
   usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741)
   vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107)
   kthread (kernel/kthread.c:436)
  The buggy address belongs to the object at ffff88801e696a00
   which belongs to the cache kmalloc-256 of size 256
  The buggy address is located 0 bytes to the right of
   allocated 208-byte region [ffff88801e696a00, ffff88801e696ad0)

Record the allocated packet count per endpoint and clamp both the adopted
count and the packet-size copy to it. Fold the Format Type II delimiter
into urb_packs before the allocation loop so the recorded limit matches
every URB.

## Remediation

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