---
id: CVE-2026-72347
title: 'netfilter: xt_connmark: reject invalid shift parameters'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: xt_connmark: reject invalid shift parameters

  Revision 2 of the CONNMARK target accepts user-controlled shift
  parameters and applies them to 32-bit mark valu…
severity: high
cvss: 7.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    d8ce63d928b457fba7ed1e302492dfd32293671c
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    9657bb11a6376ab0a79f05d433713d6944111e9d
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    8ace320ac4416f5e5fbcd065309fb2dfcce787b0
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    c3fa852d117b3fda72265e4230e3967db4a74fcf
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    4eef84b09a3836919360c4232b0f16651a155eec
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    230173cc6105bdfb2696d37e6e56687b003fbe63
  - >-
    Linux >= 472a73e00757b971d613d796374d2727b2e4954d <
    1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc
  - Linux 4.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T18:47:35.760331Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:19.565Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72347'
references:
  - url: 'https://git.kernel.org/stable/c/d8ce63d928b457fba7ed1e302492dfd32293671c'
  - url: 'https://git.kernel.org/stable/c/9657bb11a6376ab0a79f05d433713d6944111e9d'
  - url: 'https://git.kernel.org/stable/c/8ace320ac4416f5e5fbcd065309fb2dfcce787b0'
  - url: 'https://git.kernel.org/stable/c/c3fa852d117b3fda72265e4230e3967db4a74fcf'
  - url: 'https://git.kernel.org/stable/c/4eef84b09a3836919360c4232b0f16651a155eec'
  - url: 'https://git.kernel.org/stable/c/230173cc6105bdfb2696d37e6e56687b003fbe63'
  - url: 'https://git.kernel.org/stable/c/1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc'
tags:
  - cve.org
epss: 0.00174
epssPercentile: 0.0638
ingestedAt: '2026-10-16T19:46:24.404Z'
---

## Overview

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

netfilter: xt_connmark: reject invalid shift parameters

Revision 2 of the CONNMARK target accepts user-controlled shift
parameters and applies them to 32-bit mark values in
connmark_tg_shift().

A shift_bits value of 32 or more triggers an undefined-shift bug when
the rule is evaluated. Invalid shift_dir values are also accepted and
silently fall back to the left-shift path.

Reject invalid revision-2 shift parameters in connmark_tg_check() so
malformed rules fail at installation time, before they can reach the
packet path.

## Affected

- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < d8ce63d928b457fba7ed1e302492dfd32293671c`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < 9657bb11a6376ab0a79f05d433713d6944111e9d`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < 8ace320ac4416f5e5fbcd065309fb2dfcce787b0`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < c3fa852d117b3fda72265e4230e3967db4a74fcf`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < 4eef84b09a3836919360c4232b0f16651a155eec`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < 230173cc6105bdfb2696d37e6e56687b003fbe63`
- `Linux >= 472a73e00757b971d613d796374d2727b2e4954d < 1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc`
- `Linux 4.17`

## Remediation

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