---
id: CVE-2025-71098
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip6_gre: make ip6gre_header() robust

  Over the years, syzbot found many ways to crash the kernel
  in ip6gre_header() [1].

  This involves team or bonding drivers ability …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip6_gre: make ip6gre_header() robust

  Over the years, syzbot found many ways to crash the kernel
  in ip6gre_header() [1].

  This involves team or bonding drivers ability …
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'
cwe:
  - CWE-476
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 3.7.1, < 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 = 3.7
  - linux_kernel = 6.19
patched:
  - linux_kernel 6.18.4
published: '2026-01-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:20.290'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-71098'
references:
  - url: 'https://git.kernel.org/stable/c/1717357007db150c2d703f13f5695460e960f26c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/17e7386234f740f3e7d5e58a47b5847ea34c3bc2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/41a1a3140aff295dee8063906f70a514548105e8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5fe210533e3459197eabfdbf97327dacbdc04d60'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/91a2b25be07ce1a7549ceebbe82017551d2eec92'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/adee129db814474f2f81207bd182bf343832a52e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/db5b4e39c4e63700c68a7e65fc4e1f1375273476'
    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: '2026-06-10T20:41:13.938305Z'
ingestedAt: '2026-09-08T15:33:26.995Z'
---

## Overview

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

ip6_gre: make ip6gre_header() robust

Over the years, syzbot found many ways to crash the kernel
in ip6gre_header() [1].

This involves team or bonding drivers ability to dynamically
change their dev->needed_headroom and/or dev->hard_header_len

In this particular crash mld_newpack() allocated an skb
with a too small reserve/headroom, and by the time mld_sendpack()
was called, syzbot managed to attach an ip6gre device.

[1]
skbuff: skb_under_panic: text:ffffffff8a1d69a8 len:136 put:40 head:ffff888059bc7000 data:ffff888059bc6fe8 tail:0x70 end:0x6c0 dev:team0
------------[ cut here ]------------
 kernel BUG at net/core/skbuff.c:213 !
 <TASK>
  skb_under_panic net/core/skbuff.c:223 [inline]
  skb_push+0xc3/0xe0 net/core/skbuff.c:2641
  ip6gre_header+0xc8/0x790 net/ipv6/ip6_gre.c:1371
  dev_hard_header include/linux/netdevice.h:3436 [inline]
  neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618
  neigh_output include/net/neighbour.h:556 [inline]
  ip6_finish_output2+0xfb3/0x1480 net/ipv6/ip6_output.c:136
 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
  ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:220
  NF_HOOK_COND include/linux/netfilter.h:307 [inline]
  ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247
  NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318
  mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855
  mld_send_cr net/ipv6/mcast.c:2154 [inline]
  mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693

## Affected

- `linux_kernel >= 3.7.1, < 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 = 3.7`
- `linux_kernel = 6.19`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.18.4`