---
id: CVE-2025-39764
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ctnetlink: remove refcounting in expectation dumpers

  Same pattern as previous patch: do not keep the expectation object
  alive via refcount, only store a coo…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ctnetlink: remove refcounting in expectation dumpers

  Same pattern as previous patch: do not keep the expectation object
  alive via refcount, only store a coo…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.23, < 6.16.2'
  - linux_kernel = 6.17
patched:
  - linux_kernel 6.16.2
published: '2025-09-11'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:00.120'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39764'
references:
  - url: 'https://git.kernel.org/stable/c/078d33c95bf534d37aa04269d1ae6158e20082d5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1492e3dcb2be3aa46d1963da96aa9593e4e4db5a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/64b7684042246e3238464c66894e30ba30c7e851'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9e5021a906532ca16e2aac69c0607711e1c70b1f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a4d634ded4d3d400f115d84f654f316f249531c9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b05500444b8eb97644efdd180839a04a706be97c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bada48ad5b0590e318d0f79636ff62a2ef9f4955'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00173
epssPercentile: 0.06759
ingestedAt: '2026-09-08T15:33:26.997Z'
---

## Overview

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

netfilter: ctnetlink: remove refcounting in expectation dumpers

Same pattern as previous patch: do not keep the expectation object
alive via refcount, only store a cookie value and then use that
as the skip hint for dump resumption.

AFAICS this has the same issue as the one resolved in the conntrack
dumper, when we do
  if (!refcount_inc_not_zero(&exp->use))

to increment the refcount, there is a chance that exp == last, which
causes a double-increment of the refcount and subsequent memory leak.

## Affected

- `linux_kernel >= 2.6.23, < 6.16.2`
- `linux_kernel = 6.17`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.16.2`