---
id: CVE-2025-71097
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: Fix reference count leak when using error routes with nexthop objects

  When a nexthop object is deleted, it is marked as dead and then
  fib_table_flush() is called…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: Fix reference count leak when using error routes with nexthop objects

  When a nexthop object is deleted, it is marked as dead and then
  fib_table_flush() is called…
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 >= 5.3.1, < 5.10.248'
  - 'linux_kernel >= 5.11, < 5.15.198'
  - 'linux_kernel >= 5.16, < 6.1.160'
  - 'linux_kernel >= 6.2, < 6.6.120'
  - 'linux_kernel >= 6.7, < 6.12.64'
  - 'linux_kernel >= 6.13, < 6.18.4'
  - linux_kernel = 5.3
  - linux_kernel = 6.19
patched:
  - linux_kernel 6.18.4
published: '2026-01-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:19.747'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-71097'
references:
  - url: 'https://git.kernel.org/stable/c/30386e090c49e803c0616a7147e43409c32a2b0e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/33ff5c207c873215e54e6176624ed57423cb7dea'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5979338c83012110ccd45cae6517591770bfe536'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5de7ad7e18356e39e8fbf7edd185a5faaf4f385a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ac782f4e3bfcde145b8a7f8af31d9422d94d172a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e3fc381320d04e4a74311e576a86cac49a16fc43'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ee4183501ea556dca31f5ffd8690aa9fd25b609f'
    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-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.0014
epssPercentile: 0.03358
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-10T20:40:27.713433Z'
ingestedAt: '2026-09-08T15:33:26.995Z'
---

## Overview

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

ipv4: Fix reference count leak when using error routes with nexthop objects

When a nexthop object is deleted, it is marked as dead and then
fib_table_flush() is called to flush all the routes that are using the
dead nexthop.

The current logic in fib_table_flush() is to only flush error routes
(e.g., blackhole) when it is called as part of network namespace
dismantle (i.e., with flush_all=true). Therefore, error routes are not
flushed when their nexthop object is deleted:

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip route add 198.51.100.1/32 nhid 1
 # ip route add blackhole 198.51.100.2/32 nhid 1
 # ip nexthop del id 1
 # ip route show
 blackhole 198.51.100.2 nhid 1 dev dummy1

As such, they keep holding a reference on the nexthop object which in
turn holds a reference on the nexthop device, resulting in a reference
count leak:

 # ip link del dev dummy1
 [   70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2

Fix by flushing error routes when their nexthop is marked as dead.

IPv6 does not suffer from this problem.

## Affected

- `linux_kernel >= 5.3.1, < 5.10.248`
- `linux_kernel >= 5.11, < 5.15.198`
- `linux_kernel >= 5.16, < 6.1.160`
- `linux_kernel >= 6.2, < 6.6.120`
- `linux_kernel >= 6.7, < 6.12.64`
- `linux_kernel >= 6.13, < 6.18.4`
- `linux_kernel = 5.3`
- `linux_kernel = 6.19`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.18.4`