---
id: CVE-2025-71098
title: 'ip6_gre: make ip6gre_header() robust'
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: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    17e7386234f740f3e7d5e58a47b5847ea34c3bc2
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    41a1a3140aff295dee8063906f70a514548105e8
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    adee129db814474f2f81207bd182bf343832a52e
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    1717357007db150c2d703f13f5695460e960f26c
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    5fe210533e3459197eabfdbf97327dacbdc04d60
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    91a2b25be07ce1a7549ceebbe82017551d2eec92
  - >-
    Linux >= c12b395a46646bab69089ce7016ac78177f6001f <
    db5b4e39c4e63700c68a7e65fc4e1f1375273476
  - Linux 3.7
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-10T20:41:13.938305Z'
published: '2026-01-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:43:51.924Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-71098'
references:
  - url: 'https://git.kernel.org/stable/c/17e7386234f740f3e7d5e58a47b5847ea34c3bc2'
  - url: 'https://git.kernel.org/stable/c/41a1a3140aff295dee8063906f70a514548105e8'
  - url: 'https://git.kernel.org/stable/c/adee129db814474f2f81207bd182bf343832a52e'
  - url: 'https://git.kernel.org/stable/c/1717357007db150c2d703f13f5695460e960f26c'
  - url: 'https://git.kernel.org/stable/c/5fe210533e3459197eabfdbf97327dacbdc04d60'
  - url: 'https://git.kernel.org/stable/c/91a2b25be07ce1a7549ceebbe82017551d2eec92'
  - url: 'https://git.kernel.org/stable/c/db5b4e39c4e63700c68a7e65fc4e1f1375273476'
tags:
  - cve.org
epss: 0.00134
epssPercentile: 0.03251
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 >= c12b395a46646bab69089ce7016ac78177f6001f < 17e7386234f740f3e7d5e58a47b5847ea34c3bc2`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < 41a1a3140aff295dee8063906f70a514548105e8`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < adee129db814474f2f81207bd182bf343832a52e`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < 1717357007db150c2d703f13f5695460e960f26c`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < 5fe210533e3459197eabfdbf97327dacbdc04d60`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < 91a2b25be07ce1a7549ceebbe82017551d2eec92`
- `Linux >= c12b395a46646bab69089ce7016ac78177f6001f < db5b4e39c4e63700c68a7e65fc4e1f1375273476`
- `Linux 3.7`

## Remediation

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