# CVE-2026-23192: linkwatch: use __dev_put() in callers to prevent UAF

> A use-after-free in the Linux kernel linkwatch subsystem allows local attackers to execute arbitrary code or escalate privileges via race conditions.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Feb 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-23192, DEBIAN-CVE-2026-23192, GHSA-7g8g-mvq9-46w7, UBUNTU-CVE-2026-23192

## What is CVE-2026-23192?

CVE-2026-23192 is a high-severity use after free vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

linkwatch: use __dev_put() in callers to prevent UAF

After linkwatch_do_dev() calls __dev_put() to release the linkwatch
reference, the device refcount may drop to 1. At this point,
netdev_run_todo() can proceed (since linkwatch_sync_dev() sees an
empty list and returns without blocking), wait for the refcount to
become 1 via netdev_wait_allrefs_any(), and then free the device
via kobject_put().

This creates a use-after-free when __linkwatch_run_queue() tries to
call netdev_unlock_ops() on the already-freed device.

Note that adding netdev_lock_ops()/netdev_unlock_ops() pair in
netdev_run_todo() before kobject_put() would not work, because
netdev_lock_ops() is conditional - it only locks when
netdev_need_ops_lock() returns true. If the device doesn't require
ops_lock, linkwatch won't hold any lock, and netdev_run_todo()
acquiring the lock won't provide synchronization.

Fix this by moving __dev_put() from linkwatch_do_dev() to its
callers. The device reference logically pairs with de-listing the
device, so it's reasonable for the caller that did the de-listing
to release it. This allows placing __dev_put() after all device
accesses are complete, preventing UAF.

The bug can be reproduced by adding mdelay(2000) after
linkwatch_do_dev() in __linkwatch_run_queue(), then running:

  ip tuntap add mode tun name tun_test
  ip link set tun_test up
  ip link set tun_test carrier off
  ip link set tun_test carrier on
  sleep 0.5
  ip tuntap del mode tun name tun_test

KASAN report:

 ==================================================================
 BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]
 BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
 BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245
 Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123

 CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 Workqueue: events_unbound linkwatch_event
 Call Trace:
  <TASK>
  __dump_stack lib/dump_stack.c:94 [inline]
  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
  print_address_description mm/kasan/report.c:378 [inline]
  print_report+0x156/0x4c9 mm/kasan/report.c:482
  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]
  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245
  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304
  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
  process_scheduled_works kernel/workqueue.c:3340 [inline]
  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
  kthread+0x3b3/0x730 kernel/kthread.c:463
  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
  </TASK>
 ==================================================================

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-23192?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23192?

Apply the vendor's patch.

## Is CVE-2026-23192 being exploited?

There is no known exploitation of CVE-2026-23192 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23192 and fix it if it is affected.

What it is: CVE-2026-23192 is a high-severity use after free vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23192 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-23192/ (Markdown: https://insights.sbomify.com/CVE-2026-23192/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23192
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23192
- OSV: https://osv.dev/vulnerability/CVE-2026-23192

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23192/
Summaries are generated and may contain mistakes; the official description above is the record.