---
id: CVE-2026-64331
title: 'usbip: vudc: fix NULL deref in vep_dequeue()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  usbip: vudc: fix NULL deref in vep_dequeue()

  vep_alloc_request() wasn't initializing vrequest->udc, so cancellations
  on the FunctionFS AIO path were arriving in vep_de…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    9858c91d9ee6a13c45311569039413729fc9b757
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    1226293ec9bed3d4cc5b05eeeb811d315ca51652
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    3750f75f29f99c0223601e2ee73ad084adec47bd
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    0025276175fbbe0dcbf3f84d090b0adee769e9d9
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    347b59e9f96719d89b6ef555d02a18ada1a5846f
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    0443e4416aa1ee97748d1ed904eaf3352c60045e
  - >-
    Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 <
    c5371e0b91b24159a3ebaa61e70b0980bcf03c0a
  - Linux 4.7
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:35:21.455334Z'
published: '2026-07-25'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:44:45.966Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64331'
references:
  - url: 'https://git.kernel.org/stable/c/9858c91d9ee6a13c45311569039413729fc9b757'
  - url: 'https://git.kernel.org/stable/c/1226293ec9bed3d4cc5b05eeeb811d315ca51652'
  - url: 'https://git.kernel.org/stable/c/3750f75f29f99c0223601e2ee73ad084adec47bd'
  - url: 'https://git.kernel.org/stable/c/d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97'
  - url: 'https://git.kernel.org/stable/c/0025276175fbbe0dcbf3f84d090b0adee769e9d9'
  - url: 'https://git.kernel.org/stable/c/347b59e9f96719d89b6ef555d02a18ada1a5846f'
  - url: 'https://git.kernel.org/stable/c/0443e4416aa1ee97748d1ed904eaf3352c60045e'
  - url: 'https://git.kernel.org/stable/c/c5371e0b91b24159a3ebaa61e70b0980bcf03c0a'
tags:
  - cve.org
epss: 0.00123
epssPercentile: 0.02029
ingestedAt: '2026-11-06T16:57:43.198Z'
---

## Overview

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

usbip: vudc: fix NULL deref in vep_dequeue()

vep_alloc_request() wasn't initializing vrequest->udc, so cancellations
on the FunctionFS AIO path were arriving in vep_dequeue without a valid
UDC reference.

Since vrequest->udc is never actually properly used anywhere, we opt to
remove it, and update vep_dequeue to obtain a reference to the udc with
ep_to_vudc(), consistent with the other vep_ ops.

AFAICT this bug has existed for ~10 years. Seems that nobody has really
stressed the FunctionFS AIO path on usbip's vudc.

I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints
via AIO. Before the fix, running `usbip attach` from the host would
cause the guest to oops with the following backtrace:

Call trace:
 vep_dequeue+0x1c/0xe4 (P)
 usb_ep_dequeue+0x14/0x20
 ffs_aio_cancel+0x24/0x34
 __arm64_sys_io_cancel+0xb0/0x124
 do_el0_svc+0x68/0x100
 el0_svc+0x18/0x5c
 el0t_64_sync_handler+0x98/0xdc
 el0t_64_sync+0x154/0x158

## Affected

- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 9858c91d9ee6a13c45311569039413729fc9b757`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 1226293ec9bed3d4cc5b05eeeb811d315ca51652`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 3750f75f29f99c0223601e2ee73ad084adec47bd`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 0025276175fbbe0dcbf3f84d090b0adee769e9d9`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 347b59e9f96719d89b6ef555d02a18ada1a5846f`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < 0443e4416aa1ee97748d1ed904eaf3352c60045e`
- `Linux >= b6a0ca11186759ad7045d68a5447b1e89f658384 < c5371e0b91b24159a3ebaa61e70b0980bcf03c0a`
- `Linux 4.7`

## Remediation

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