---
id: CVE-2026-64554
title: 'netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()

  br_ip6_fragment() gets prevhdr, a pointer into the skb head, from
  ip6_find_1stfragopt(), then calls s…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    8c10778ec674b67a07ea042fcba64270f3f38a5a
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    2731efa6364e47934c96eb69e01ea131e8af8030
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    00c06ef8c018493943891a7d0ca82b71b24f3180
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    c141f69d0a0fb16964dbc293650047e69bda8af7
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    f2e6596d10783557aeb9668da2a3b4d19deb2001
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    1c4f67c89fd27c4df4c70b135c2c59627698b3c0
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    4ac981a8b7ce7aec99a52d08f8a8953e8e120067
  - >-
    Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 <
    86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d
  - Linux 5.3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:42:31.205965Z'
published: '2026-07-27'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:52:52.280Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64554'
references:
  - url: 'https://git.kernel.org/stable/c/8c10778ec674b67a07ea042fcba64270f3f38a5a'
  - url: 'https://git.kernel.org/stable/c/2731efa6364e47934c96eb69e01ea131e8af8030'
  - url: 'https://git.kernel.org/stable/c/00c06ef8c018493943891a7d0ca82b71b24f3180'
  - url: 'https://git.kernel.org/stable/c/c141f69d0a0fb16964dbc293650047e69bda8af7'
  - url: 'https://git.kernel.org/stable/c/f2e6596d10783557aeb9668da2a3b4d19deb2001'
  - url: 'https://git.kernel.org/stable/c/1c4f67c89fd27c4df4c70b135c2c59627698b3c0'
  - url: 'https://git.kernel.org/stable/c/4ac981a8b7ce7aec99a52d08f8a8953e8e120067'
  - url: 'https://git.kernel.org/stable/c/86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d'
tags:
  - cve.org
epss: 0.00255
epssPercentile: 0.15954
ingestedAt: '2026-10-16T17:24:46.832Z'
---

## Overview

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

netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()

br_ip6_fragment() gets prevhdr, a pointer into the skb head, from
ip6_find_1stfragopt(), then calls skb_checksum_help().  For a cloned skb
skb_checksum_help() reallocates the head via pskb_expand_head(), leaving
prevhdr dangling.  It is later dereferenced in ip6_frag_next(), causing a
use-after-free write.

Save prevhdr's offset before skb_checksum_help() and recompute it after,
like commit ef0efcd3bd3f ("ipv6: Fix dangling pointer when ipv6
fragment").

  BUG: KASAN: slab-use-after-free in ip6_frag_next (net/ipv6/ip6_output.c:857)
  Write of size 1 at addr ffff888013ff5016 by task exploit/141
  Call Trace:
   ...
   kasan_report (mm/kasan/report.c:595)
   ip6_frag_next (net/ipv6/ip6_output.c:857)
   br_ip6_fragment (net/ipv6/netfilter.c:212)
   nf_ct_bridge_post (net/bridge/netfilter/nf_conntrack_bridge.c:407)
   nf_hook_slow (net/netfilter/core.c:619)
   br_forward_finish (net/bridge/br_forward.c:66)
   __br_forward (net/bridge/br_forward.c:115)
   maybe_deliver (net/bridge/br_forward.c:191)
   br_flood (net/bridge/br_forward.c:245)
   br_handle_frame_finish (net/bridge/br_input.c:229)
   br_handle_frame (net/bridge/br_input.c:442)
   ...
   packet_sendmsg (net/packet/af_packet.c:3114)
   ...
   do_syscall_64 (arch/x86/entry/syscall_64.c:94)
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
  Kernel panic - not syncing: Fatal exception in interrupt

## Affected

- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 8c10778ec674b67a07ea042fcba64270f3f38a5a`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 2731efa6364e47934c96eb69e01ea131e8af8030`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 00c06ef8c018493943891a7d0ca82b71b24f3180`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < c141f69d0a0fb16964dbc293650047e69bda8af7`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < f2e6596d10783557aeb9668da2a3b4d19deb2001`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 1c4f67c89fd27c4df4c70b135c2c59627698b3c0`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 4ac981a8b7ce7aec99a52d08f8a8953e8e120067`
- `Linux >= 764dd163ac922f8683b5bcd3007251ce7b26cd33 < 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d`
- `Linux 5.3`

## Remediation

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