---
id: CVE-2025-71097
title: 'ipv4: Fix reference count leak when using error routes with nexthop objects'
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: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    5de7ad7e18356e39e8fbf7edd185a5faaf4f385a
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    33ff5c207c873215e54e6176624ed57423cb7dea
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    30386e090c49e803c0616a7147e43409c32a2b0e
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    5979338c83012110ccd45cae6517591770bfe536
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    ee4183501ea556dca31f5ffd8690aa9fd25b609f
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    e3fc381320d04e4a74311e576a86cac49a16fc43
  - >-
    Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e <
    ac782f4e3bfcde145b8a7f8af31d9422d94d172a
  - Linux 5.3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-10T20:40:27.713433Z'
published: '2026-01-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:43:50.602Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-71097'
references:
  - url: 'https://git.kernel.org/stable/c/5de7ad7e18356e39e8fbf7edd185a5faaf4f385a'
  - url: 'https://git.kernel.org/stable/c/33ff5c207c873215e54e6176624ed57423cb7dea'
  - url: 'https://git.kernel.org/stable/c/30386e090c49e803c0616a7147e43409c32a2b0e'
  - url: 'https://git.kernel.org/stable/c/5979338c83012110ccd45cae6517591770bfe536'
  - url: 'https://git.kernel.org/stable/c/ee4183501ea556dca31f5ffd8690aa9fd25b609f'
  - url: 'https://git.kernel.org/stable/c/e3fc381320d04e4a74311e576a86cac49a16fc43'
  - url: 'https://git.kernel.org/stable/c/ac782f4e3bfcde145b8a7f8af31d9422d94d172a'
tags:
  - cve.org
epss: 0.00134
epssPercentile: 0.0325
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 >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < 5de7ad7e18356e39e8fbf7edd185a5faaf4f385a`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < 33ff5c207c873215e54e6176624ed57423cb7dea`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < 30386e090c49e803c0616a7147e43409c32a2b0e`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < 5979338c83012110ccd45cae6517591770bfe536`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < ee4183501ea556dca31f5ffd8690aa9fd25b609f`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < e3fc381320d04e4a74311e576a86cac49a16fc43`
- `Linux >= 493ced1ac47c48bb86d9d4e8e87df8592be85a0e < ac782f4e3bfcde145b8a7f8af31d9422d94d172a`
- `Linux 5.3`

## Remediation

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