---
id: CVE-2026-99073
title: 'ipv4: stop exception dump when nexthop group shrinks'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: stop exception dump when nexthop group shrinks

  Commit 4ce5dc9316de ("inet: switch inet_dump_fib() to RCU
  protection") allowed IPv4 FIB dumps to run concurrently …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece <
    f91e472821e32f58b03eb631e20a67157e2b928b
  - >-
    Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece <
    21cba134c30c17ae55f468b5809336437df5d7e6
  - >-
    Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece <
    b9a30bb7b831e8c5a47fadbdf1760918aaf009cc
  - >-
    Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece <
    4f4afc07dcb2edd4f9afa36595373f8cdb9b58c2
  - Linux 6.9
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T12:23:16.935Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99073'
references:
  - url: 'https://git.kernel.org/stable/c/f91e472821e32f58b03eb631e20a67157e2b928b'
  - url: 'https://git.kernel.org/stable/c/21cba134c30c17ae55f468b5809336437df5d7e6'
  - url: 'https://git.kernel.org/stable/c/b9a30bb7b831e8c5a47fadbdf1760918aaf009cc'
  - url: 'https://git.kernel.org/stable/c/4f4afc07dcb2edd4f9afa36595373f8cdb9b58c2'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.515Z'
---

## Overview

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

ipv4: stop exception dump when nexthop group shrinks

Commit 4ce5dc9316de ("inet: switch inet_dump_fib() to RCU
protection") allowed IPv4 FIB dumps to run concurrently with nexthop
replacement.

fib_dump_info_fnhe() uses fib_info_num_path() as the loop bound,
then fib_info_nhc() independently reloads nh->nh_grp. If
RTM_NEWNEXTHOP replaces a group with fewer paths between those loads,
fib_info_nhc() returns NULL and the dump dereferences it through
nhc_flags.

Stop the walk when the indexed path is absent. Nexthop groups are
dense, so the current snapshot has no later path.

## Affected

- `Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece < f91e472821e32f58b03eb631e20a67157e2b928b`
- `Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece < 21cba134c30c17ae55f468b5809336437df5d7e6`
- `Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece < b9a30bb7b831e8c5a47fadbdf1760918aaf009cc`
- `Linux >= 4ce5dc9316de50e0da84beafe55d1344f829cece < 4f4afc07dcb2edd4f9afa36595373f8cdb9b58c2`
- `Linux 6.9`

## Remediation

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