---
id: CVE-2026-74579
title: 'netfilter: nft_payload: fix mask build for partial field offload'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nft_payload: fix mask build for partial field offload

  nft_payload_offload_mask() builds the offload match mask for a payload
  expression that covers only par…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    3ee7b3f813b11f28cd6efdf7f24d64b5a7fd4dc7
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    8720df4504e0ed1781a702f65251bd47b3534d5e
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    363c3a84a946d53e5e121c9f47c7c2b7d228c46b
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    b19b5d2e042c294e2cc1c908dc598f9d64015396
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    a375d8ace807767f29f276b681b6324c74929b1d
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    16b553c46e347bc9de9946c4960654d5884a86de
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    630295d5bba1d0e0f494cc459452eb0a0058c545
  - >-
    Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 <
    39e88f28fb32bf02bd4b525c24c842c9cff5663d
  - Linux 5c2b4b4f9fa5b765b927e361e3d310bcb5773015
  - Linux >= 5.9.14 < 5.10
  - Linux 5.10
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T19:01:02.815654Z'
published: '2026-08-17'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:57.728Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74579'
references:
  - url: 'https://git.kernel.org/stable/c/3ee7b3f813b11f28cd6efdf7f24d64b5a7fd4dc7'
  - url: 'https://git.kernel.org/stable/c/8720df4504e0ed1781a702f65251bd47b3534d5e'
  - url: 'https://git.kernel.org/stable/c/363c3a84a946d53e5e121c9f47c7c2b7d228c46b'
  - url: 'https://git.kernel.org/stable/c/b19b5d2e042c294e2cc1c908dc598f9d64015396'
  - url: 'https://git.kernel.org/stable/c/a375d8ace807767f29f276b681b6324c74929b1d'
  - url: 'https://git.kernel.org/stable/c/16b553c46e347bc9de9946c4960654d5884a86de'
  - url: 'https://git.kernel.org/stable/c/630295d5bba1d0e0f494cc459452eb0a0058c545'
  - url: 'https://git.kernel.org/stable/c/39e88f28fb32bf02bd4b525c24c842c9cff5663d'
tags:
  - cve.org
epss: 0.0012
epssPercentile: 0.01706
ingestedAt: '2026-10-16T19:46:24.340Z'
---

## Overview

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

netfilter: nft_payload: fix mask build for partial field offload

nft_payload_offload_mask() builds the offload match mask for a payload
expression that covers only part of a header field.  For a partial IPv6
address match (field_len = 16, priv_len = 1) that shift is 1 << 120, which
is undefined on the 32-bit int operand.  It also trims only one word, so
the remaining words stay 0xffffffff (and when priv_len is a multiple of 4
the trim is skipped entirely), leaving the mask covering more bytes than
the rule matches.

  UBSAN: shift-out-of-bounds in net/netfilter/nft_payload.c:278:20
  shift exponent 120 is too large for 32-bit type 'int'
  ...

The match is byte-granular and struct nft_data is zero-initialised, so the
correct mask is simply the first priv_len bytes set to 0xff. Set those
bytes directly and drop the word/shift trimming; this removes the undefined
shift and no longer over-masks the trailing bytes.

## Affected

- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 3ee7b3f813b11f28cd6efdf7f24d64b5a7fd4dc7`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 8720df4504e0ed1781a702f65251bd47b3534d5e`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 363c3a84a946d53e5e121c9f47c7c2b7d228c46b`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < b19b5d2e042c294e2cc1c908dc598f9d64015396`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < a375d8ace807767f29f276b681b6324c74929b1d`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 16b553c46e347bc9de9946c4960654d5884a86de`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 630295d5bba1d0e0f494cc459452eb0a0058c545`
- `Linux >= a5d45bc0dc50f9dd83703510e9804d813a9cac32 < 39e88f28fb32bf02bd4b525c24c842c9cff5663d`
- `Linux 5c2b4b4f9fa5b765b927e361e3d310bcb5773015`
- `Linux >= 5.9.14 < 5.10`
- `Linux 5.10`

## Remediation

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