---
id: CVE-2026-52915
title: 'netfilter: ip6t_hbh: reject oversized option lists'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ip6t_hbh: reject oversized option lists

  struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors,
  but hbh_mt6_check() does not reject larger opts…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    2d523ba48d4ecc46acfb6aba548292cfcce1ac02
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    588933f1a2ca5ff99274f8c9f25dc3a25d0191c3
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    784aadea7a108c9f90985683caa87fb0198c6a39
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    41ec2e242f1702e8370ddfe14d22b7a766021c3e
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    db0250470f023f159094052c0bd5ab026a88ae93
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    57b0ac5e1b46f1f0338dff392ef2092e2871b412
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6feb43c0995ab3a9c826707eb46541a1696fe4f7
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    4322dcde6b4173c2d8e8e6118ed290794263bcc8
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T15:22:35.445064Z'
published: '2026-06-24'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:31:18.621Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-52915'
references:
  - url: 'https://git.kernel.org/stable/c/2d523ba48d4ecc46acfb6aba548292cfcce1ac02'
  - url: 'https://git.kernel.org/stable/c/588933f1a2ca5ff99274f8c9f25dc3a25d0191c3'
  - url: 'https://git.kernel.org/stable/c/784aadea7a108c9f90985683caa87fb0198c6a39'
  - url: 'https://git.kernel.org/stable/c/41ec2e242f1702e8370ddfe14d22b7a766021c3e'
  - url: 'https://git.kernel.org/stable/c/db0250470f023f159094052c0bd5ab026a88ae93'
  - url: 'https://git.kernel.org/stable/c/57b0ac5e1b46f1f0338dff392ef2092e2871b412'
  - url: 'https://git.kernel.org/stable/c/6feb43c0995ab3a9c826707eb46541a1696fe4f7'
  - url: 'https://git.kernel.org/stable/c/4322dcde6b4173c2d8e8e6118ed290794263bcc8'
tags:
  - cve.org
epss: 0.00126
epssPercentile: 0.02041
ingestedAt: '2026-10-16T17:24:46.719Z'
---

## Overview

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

netfilter: ip6t_hbh: reject oversized option lists

struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors,
but hbh_mt6_check() does not reject larger optsnr values supplied from
userspace.

Validate optsnr in the rule setup path so only match data that fits the
fixed-size opts array can be installed. This follows the existing xtables
pattern of rejecting invalid user-provided counts in checkentry() and
keeps the packet matching path unchanged.

`struct ip6t_opts` has a fixed `opts[IP6T_OPTS_OPTSNR]` array,
where `IP6T_OPTS_OPTSNR` is 16, then off-by-one array access is possible:

[  137.924693][ T8692] UBSAN: array-index-out-of-bounds in ../net/ipv6/netfilter/ip6t_hbh.c:110:29
[  137.926167][ T8692] index 16 is out of range for type '__u16 [16]'

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2d523ba48d4ecc46acfb6aba548292cfcce1ac02`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 588933f1a2ca5ff99274f8c9f25dc3a25d0191c3`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 784aadea7a108c9f90985683caa87fb0198c6a39`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 41ec2e242f1702e8370ddfe14d22b7a766021c3e`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < db0250470f023f159094052c0bd5ab026a88ae93`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 57b0ac5e1b46f1f0338dff392ef2092e2871b412`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6feb43c0995ab3a9c826707eb46541a1696fe4f7`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4322dcde6b4173c2d8e8e6118ed290794263bcc8`
- `Linux 2.6.12`

## Remediation

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