# CVE-2025-71098: ip6_gre: make ip6gre_header() robust

> A local attacker can crash the Linux kernel by triggering a null dereference in the IPv6 GRE header function via race conditions with team or bonding drivers.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2025-71098, DEBIAN-CVE-2025-71098, GHSA-qfv4-qxw7-g29f, ROOT-OS-DEBIAN-11-CVE-2025-71098, ROOT-OS-DEBIAN-12-CVE-2025-71098, ROOT-OS-DEBIAN-13-CVE-2025-71098, ROOT-OS-UBUNTU-2204-CVE-2025-71098, ROOT-OS-UBUNTU-2404-CVE-2025-71098, UBUNTU-CVE-2025-71098

## What is CVE-2025-71098?

CVE-2025-71098 is a medium-severity vulnerability in Linux kernel, published on 13 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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

Weakness: CWE-476 (NULL Pointer Dereference), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-71098?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71098?

Apply the vendor's patch.

## Is CVE-2025-71098 being exploited?

There is no known exploitation of CVE-2025-71098 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71098 and fix it if it is affected.

What it is: CVE-2025-71098 is a medium-severity vulnerability in Linux kernel, published on 13 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-71098 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-71098/ (Markdown: https://insights.sbomify.com/CVE-2025-71098/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71098
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71098
- OSV: https://osv.dev/vulnerability/CVE-2025-71098

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71098/
Summaries are generated and may contain mistakes; the official description above is the record.