# CVE-2025-71098

## Summary

- **CVE ID:** CVE-2025-71098
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Jan 13, 2026
- **Last Modified:** Sep 8, 2026

## Description

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 Products

- Linux — Linux (c12b395a46646bab69089ce7016ac78177f6001f)
- Linux — Linux (3.7)
- Linux — Linux (0)
- Linux — Linux (5.10.248)
- Linux — Linux (5.15.198)
- Linux — Linux (6.1.160)
- Linux — Linux (6.6.120)
- Linux — Linux (6.12.64)
- Linux — Linux (6.18.4)
- Linux — Linux (6.19)

## References

- [CNA](https://git.kernel.org/stable/c/17e7386234f740f3e7d5e58a47b5847ea34c3bc2)
- [CNA](https://git.kernel.org/stable/c/41a1a3140aff295dee8063906f70a514548105e8)
- [CNA](https://git.kernel.org/stable/c/adee129db814474f2f81207bd182bf343832a52e)
- [CNA](https://git.kernel.org/stable/c/1717357007db150c2d703f13f5695460e960f26c)
- [CNA](https://git.kernel.org/stable/c/5fe210533e3459197eabfdbf97327dacbdc04d60)
- [CNA](https://git.kernel.org/stable/c/91a2b25be07ce1a7549ceebbe82017551d2eec92)
- [CNA](https://git.kernel.org/stable/c/db5b4e39c4e63700c68a7e65fc4e1f1375273476)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.13%
- **EPSS Percentile:** 3.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._