---
id: CVE-2025-68366
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nbd: defer config unlock in nbd_genl_connect

  There is one use-after-free warning when running NBD_CMD_CONNECT and
  NBD_CLEAR_SOCK:

  nbd_genl_connect
    nbd_alloc_and_ini…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nbd: defer config unlock in nbd_genl_connect

  There is one use-after-free warning when running NBD_CMD_CONNECT and
  NBD_CLEAR_SOCK:

  nbd_genl_connect
    nbd_alloc_and_ini…
severity: none
published: '2025-12-24'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T11:10:00.203'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68366'
references:
  - url: 'https://git.kernel.org/stable/c/1649714b930f9ea6233ce0810ba885999da3b5d4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2e5e0665a594f076ef2b9439447bae8be293d09d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/330d688a5ca53857828081a3cf31b92ad1b0b3ed'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9a38306643874566d20f7aba7dff9e6f657b51a9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ae3e7bc1f4b393ae20e5c85583eb2c6977374716'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c9b99c948b4fb014812afe7b5ccf2db121d22e46'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c9e805f6a35d1dd189a9345595a5c20e87611942'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cd93db1b1b4460e6ee77564024ea461e5940f69c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00198
epssPercentile: 0.0883
ingestedAt: '2026-10-13T11:23:51.152Z'
---

## Overview

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

nbd: defer config unlock in nbd_genl_connect

There is one use-after-free warning when running NBD_CMD_CONNECT and
NBD_CLEAR_SOCK:

nbd_genl_connect
  nbd_alloc_and_init_config // config_refs=1
  nbd_start_device // config_refs=2
  set NBD_RT_HAS_CONFIG_REF			open nbd // config_refs=3
  recv_work done // config_refs=2
						NBD_CLEAR_SOCK // config_refs=1
						close nbd // config_refs=0
  refcount_inc -> uaf

------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 24 PID: 1014 at lib/refcount.c:25 refcount_warn_saturate+0x12e/0x290
 nbd_genl_connect+0x16d0/0x1ab0
 genl_family_rcv_msg_doit+0x1f3/0x310
 genl_rcv_msg+0x44a/0x790

The issue can be easily reproduced by adding a small delay before
refcount_inc(&nbd->config_refs) in nbd_genl_connect():

        mutex_unlock(&nbd->config_lock);
        if (!ret) {
                set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags);
+               printk("before sleep\n");
+               mdelay(5 * 1000);
+               printk("after sleep\n");
                refcount_inc(&nbd->config_refs);
                nbd_connect_reply(info, nbd->index);
        }

## Remediation

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