---
id: CVE-2025-40139
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().

  smc_clc_prfx_set() is called during connect() and not under RCU
  nor RTNL.

  Using sk_dst_get(sk)->de…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().

  smc_clc_prfx_set() is called during connect() and not under RCU
  nor RTNL.

  Using sk_dst_get(sk)->de…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
published: '2025-11-12'
updated: '2026-09-02'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-40139'
references:
  - url: 'https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/80d1fd39f4e37d836655e9f7ffccaf78925049bf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/935d783e5de9b64587f3adb25641dd8385e64ddb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/956c57daba55cf9ed25d9f2512883b8a1a927599'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00153
epssPercentile: 0.03696
ingestedAt: '2026-09-02T13:44:41.215Z'
---

## Overview

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

smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().

smc_clc_prfx_set() is called during connect() and not under RCU
nor RTNL.

Using sk_dst_get(sk)->dev could trigger UAF.

Let's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()
after kernel_getsockname().

Note that the returned value of smc_clc_prfx_set() is not used
in the caller.

While at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()
not to touch dst there.

## Remediation

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