---
id: CVE-2026-98240
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: ip_tunnel: initialize `options_len` before referencing options

  The following command triggers a kernel panic:

    ip link add d0 type dummy; ip link set d0 up
    ip…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: ip_tunnel: initialize `options_len` before referencing options

  The following command triggers a kernel panic:

    ip link add d0 type dummy; ip link set d0 up
    ip…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bb5e62f2d547c4de6d1b144cbce2373a76c33f18 <
    9907325257b4b382f26aafd5d9a8d47915907dd5
  - >-
    Linux >= bb5e62f2d547c4de6d1b144cbce2373a76c33f18 <
    0f6a6beb01c068fcd5274eabf22c260039749fea
  - >-
    Linux >= bb5e62f2d547c4de6d1b144cbce2373a76c33f18 <
    455ebeadf714f51e1dbbd6a022c74c9215b1cd76
  - Linux 6.15
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T09:18:11.960'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98240'
references:
  - url: 'https://git.kernel.org/stable/c/0f6a6beb01c068fcd5274eabf22c260039749fea'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/455ebeadf714f51e1dbbd6a022c74c9215b1cd76'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9907325257b4b382f26aafd5d9a8d47915907dd5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-06T08:50:17.434Z'
---

## Overview

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

net: ip_tunnel: initialize `options_len` before referencing options

The following command triggers a kernel panic:

  ip link add d0 type dummy; ip link set d0 up
  ip route add 10.30.0.0/16 \
    encap ip id 300 geneve_opts 4660:66:11223344 dev d0

  memcpy: detected buffer overflow: 4 byte write of buffer size 0
  kernel BUG at lib/string_helpers.c:1044!
  ...
  ip_tun_parse_opts.part.0.cold+0x10/0x10
  ip_tun_build_state+0x116/0x2a0

On kernels built with GCC 15+ and `CONFIG_FORTIFY_SOURCE`, the fortified
`memcpy()` got 0 sized destination with request of 4 bytes length:

  static int ip_tun_parse_opts_geneve(...)
  {
      ...
      attr = tb[LWTUNNEL_IP_OPT_GENEVE_DATA];
      data_len = nla_len(attr); /* == 4 */

      struct geneve_opt *opt = ip_tunnel_info_opts(info) + opts_len;
      memcpy(opt->opt_data, nla_data(attr), data_len);
      /*     ^^^^^^^^^^^^^ 0 since options_len is assigned afterwards */

Fixed by initializing the counter before the options are referenced.
Matching what `tunnel_key_opts_set()` already does.

## Remediation

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