---
id: CVE-2026-98485
title: 'netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read

  rt_mt6_check() permits rules to be configured with rtinfo->addrnr == 0
  even when address match…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    959d1829d1ce8b91b435b24a923b51bcc8897090
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    fe336bab13834394320997de8b16ca4a913b4f13
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    5a54f8b7f7fe207a5c14713015a5820588faf1ad
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    b89249819a7d6698bed152feafd3bc6c08489d15
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    dd55c0ea87bf70e4e4b3b683acd29ef981335b26
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    191239b0939692e92459d8d32cad14247fa93f89
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    d9cf4ac6f326330e1fe4d95671d36a6ff3593f64
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    82313c169eddc02b1bf5ba6b427803e272d3ec42
  - Linux 2.6.12
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:16:00.435Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98485'
references:
  - url: 'https://git.kernel.org/stable/c/959d1829d1ce8b91b435b24a923b51bcc8897090'
  - url: 'https://git.kernel.org/stable/c/fe336bab13834394320997de8b16ca4a913b4f13'
  - url: 'https://git.kernel.org/stable/c/5a54f8b7f7fe207a5c14713015a5820588faf1ad'
  - url: 'https://git.kernel.org/stable/c/b89249819a7d6698bed152feafd3bc6c08489d15'
  - url: 'https://git.kernel.org/stable/c/dd55c0ea87bf70e4e4b3b683acd29ef981335b26'
  - url: 'https://git.kernel.org/stable/c/191239b0939692e92459d8d32cad14247fa93f89'
  - url: 'https://git.kernel.org/stable/c/d9cf4ac6f326330e1fe4d95671d36a6ff3593f64'
  - url: 'https://git.kernel.org/stable/c/82313c169eddc02b1bf5ba6b427803e272d3ec42'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.294Z'
---

## Overview

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

netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read

rt_mt6_check() permits rules to be configured with rtinfo->addrnr == 0
even when address matching (IP6T_RT_FST_MASK) is requested.

In the IP6T_RT_FST_NSTRICT path, rt_mt6() evaluates packet routing
addresses against rtinfo->addrs[i] and terminates backwards at the bottom
of the loop:

    if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
        i++;
    }
    if (i == rtinfo->addrnr)
        break;

When addrnr is 0, if the first packet address matches rtinfo->addrs[0],
i is incremented to 1. Because i is now strictly greater than addrnr (0),
the loop termination condition (i == rtinfo->addrnr) is bypassed and will
never be satisfied.

If a crafted IPv6 packet contains matching routing addresses, i will
advance past IP6T_RT_HOPS (16). The subsequent call to ipv6_addr_equal()
reads beyond struct ip6t_rt, triggering UBSAN/KASAN out-of-bounds warnings
or kernel panics.

Fix this by:
1. Rejecting rules in rt_mt6_check() where IP6T_RT_FST_MASK is set but
   rtinfo->addrnr is zero.
2. In rt_mt6(), moving the termination condition (i < rtinfo->addrnr)
   into the for-loop header condition and removing the backwards break
   at the end of the loop body.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 959d1829d1ce8b91b435b24a923b51bcc8897090`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < fe336bab13834394320997de8b16ca4a913b4f13`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5a54f8b7f7fe207a5c14713015a5820588faf1ad`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < b89249819a7d6698bed152feafd3bc6c08489d15`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dd55c0ea87bf70e4e4b3b683acd29ef981335b26`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 191239b0939692e92459d8d32cad14247fa93f89`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < d9cf4ac6f326330e1fe4d95671d36a6ff3593f64`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 82313c169eddc02b1bf5ba6b427803e272d3ec42`
- `Linux 2.6.12`

## Remediation

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