---
id: CVE-2026-98596
title: 'ipv6: Fix dst leak for uncached routes.'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: Fix dst leak for uncached routes.

  ip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check()
  detect an uncached route by list_empty(&rt->dst.rt_uncached),…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 98aa546af5e4f180439c82da403cc77926d3953b <
    5045aa25f3790dcdb158a58ac60ccf8da42959aa
  - >-
    Linux >= 98aa546af5e4f180439c82da403cc77926d3953b <
    ed902d5546fb9c142b3216d8eec914fa1bc0aa80
  - >-
    Linux >= 98aa546af5e4f180439c82da403cc77926d3953b <
    f9722746df13a8a29103c847ef56b02c11ce0963
  - >-
    Linux >= 98aa546af5e4f180439c82da403cc77926d3953b <
    be31fe6333f534155e6b408f1ef6d77974bb41aa
  - Linux 6.11
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:09.189Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98596'
references:
  - url: 'https://git.kernel.org/stable/c/5045aa25f3790dcdb158a58ac60ccf8da42959aa'
  - url: 'https://git.kernel.org/stable/c/ed902d5546fb9c142b3216d8eec914fa1bc0aa80'
  - url: 'https://git.kernel.org/stable/c/f9722746df13a8a29103c847ef56b02c11ce0963'
  - url: 'https://git.kernel.org/stable/c/be31fe6333f534155e6b408f1ef6d77974bb41aa'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.246Z'
---

## Overview

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

ipv6: Fix dst leak for uncached routes.

ip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check()
detect an uncached route by list_empty(&rt->dst.rt_uncached),
which replaced the static DST_NOCACHE flag check in commit
a4c2fd7f7891 ("net: remove DST_NOCACHE flag").

When a device is unregistered, rt6_uncached_list_flush_dev()
unlinks uncached routes tied to the device from rt6_uncached_list.

Previously, they were moved to another list with list_move()
(__list_del_entry() + list_add()), and since commit 98aa546af5e4
("inet: remove (struct uncached_list)->quarantine"), the routes
are just unlinked with list_del_init().

If list_del_init() runs concurrently, list_empty() evaluates to
true; ip6_route_output_flags() calls dst_hold_safe() incorrectly
and ip6_rt_put_flags() skips ip6_rt_put(), leaking dst, and thus
dev tied via rt->from as well.

The same race is partially fixed by commit 9a6f0c4d5796 ("dst:
fix races in rt6_uncached_list_del() and rt_del_uncached_list()").

Let's check rt6->dst.rt_uncached_list instead.

Note that IPv4 does not have the same issue.

## Affected

- `Linux >= 98aa546af5e4f180439c82da403cc77926d3953b < 5045aa25f3790dcdb158a58ac60ccf8da42959aa`
- `Linux >= 98aa546af5e4f180439c82da403cc77926d3953b < ed902d5546fb9c142b3216d8eec914fa1bc0aa80`
- `Linux >= 98aa546af5e4f180439c82da403cc77926d3953b < f9722746df13a8a29103c847ef56b02c11ce0963`
- `Linux >= 98aa546af5e4f180439c82da403cc77926d3953b < be31fe6333f534155e6b408f1ef6d77974bb41aa`
- `Linux 6.11`

## Remediation

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