---
id: CVE-2026-72350
title: 'netfilter: xt_u32: reject invalid shift counts'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: xt_u32: reject invalid shift counts

  u32_match_it() executes rule-supplied shift operands on a 32-bit
  value. A malformed u32 rule can provide a shift count o…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    ca7c92d9701249e6daf132087756a88cbf2bb2a3
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    b33b44250d57ab0e5a1e2571b5285fb0d0a7f382
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    728f479dc0447ae7eaef87926ff49142e415a811
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    0a8b7a6d763775709c601f584e709ae48bcc000a
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    cce42014415cecd98aa49b3950e7b02ee7c81268
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    a597a722fb71a534138c20359b655726622b5f17
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    00d034fe8230dfc5832fe011ff2d81c1a2cc7a29
  - >-
    Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de <
    64cdf7d30ac18e43df6c48004435febb965809a8
  - Linux 2.6.23
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:47:46.235964Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:19.841Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72350'
references:
  - url: 'https://git.kernel.org/stable/c/ca7c92d9701249e6daf132087756a88cbf2bb2a3'
  - url: 'https://git.kernel.org/stable/c/b33b44250d57ab0e5a1e2571b5285fb0d0a7f382'
  - url: 'https://git.kernel.org/stable/c/728f479dc0447ae7eaef87926ff49142e415a811'
  - url: 'https://git.kernel.org/stable/c/0a8b7a6d763775709c601f584e709ae48bcc000a'
  - url: 'https://git.kernel.org/stable/c/cce42014415cecd98aa49b3950e7b02ee7c81268'
  - url: 'https://git.kernel.org/stable/c/a597a722fb71a534138c20359b655726622b5f17'
  - url: 'https://git.kernel.org/stable/c/00d034fe8230dfc5832fe011ff2d81c1a2cc7a29'
  - url: 'https://git.kernel.org/stable/c/64cdf7d30ac18e43df6c48004435febb965809a8'
tags:
  - cve.org
epss: 0.00176
epssPercentile: 0.06647
ingestedAt: '2026-10-16T19:46:24.404Z'
---

## Overview

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

netfilter: xt_u32: reject invalid shift counts

u32_match_it() executes rule-supplied shift operands on a 32-bit
value. A malformed u32 rule can provide a shift count of 32 or more,
triggering an undefined shift out-of-bounds during packet evaluation.

Validate XT_U32_LEFTSH and XT_U32_RIGHTSH operands in
u32_mt_checkentry() and reject malformed rules before they reach the
packet path.

## Affected

- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < ca7c92d9701249e6daf132087756a88cbf2bb2a3`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < b33b44250d57ab0e5a1e2571b5285fb0d0a7f382`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < 728f479dc0447ae7eaef87926ff49142e415a811`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < 0a8b7a6d763775709c601f584e709ae48bcc000a`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < cce42014415cecd98aa49b3950e7b02ee7c81268`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < a597a722fb71a534138c20359b655726622b5f17`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < 00d034fe8230dfc5832fe011ff2d81c1a2cc7a29`
- `Linux >= 1b50b8a371e90a5e110f466e4ac02cf6b5f681de < 64cdf7d30ac18e43df6c48004435febb965809a8`
- `Linux 2.6.23`

## Remediation

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