---
id: CVE-2026-31428
title: 'netfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD

  __build_packet_message() manually constructs the NFULA_PAYLOAD netlink
  attribute using skb_pu…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    7f3e5d72455936f42709116fabeca3bb216cda62
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    21d8efda029948d3666b0db5afcc0d36c0984aae
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    fc961dd7272b5e4a462999635e44a4770d7f2482
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    a8365d1064ded323797c5e28e91070c52f44b76c
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    a2f6ff3444b663d6cfa63eadd61327a18592885a
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    c9f6c51d36482805ac3ffadb9663fe775a13e926
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    7eff72968161fb8ddb26113344de3b92fb7d7ef5
  - >-
    Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f <
    52025ebaa29f4eb4ed8bf92ce83a68f24ab7fdf7
  - Linux 2.6.24
published: '2026-04-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:47:04.591Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31428'
references:
  - url: 'https://git.kernel.org/stable/c/7f3e5d72455936f42709116fabeca3bb216cda62'
  - url: 'https://git.kernel.org/stable/c/21d8efda029948d3666b0db5afcc0d36c0984aae'
  - url: 'https://git.kernel.org/stable/c/fc961dd7272b5e4a462999635e44a4770d7f2482'
  - url: 'https://git.kernel.org/stable/c/a8365d1064ded323797c5e28e91070c52f44b76c'
  - url: 'https://git.kernel.org/stable/c/a2f6ff3444b663d6cfa63eadd61327a18592885a'
  - url: 'https://git.kernel.org/stable/c/c9f6c51d36482805ac3ffadb9663fe775a13e926'
  - url: 'https://git.kernel.org/stable/c/7eff72968161fb8ddb26113344de3b92fb7d7ef5'
  - url: 'https://git.kernel.org/stable/c/52025ebaa29f4eb4ed8bf92ce83a68f24ab7fdf7'
tags:
  - cve.org
epss: 0.00181
epssPercentile: 0.0682
ingestedAt: '2026-09-08T15:33:26.990Z'
---

## Overview

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

netfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD

__build_packet_message() manually constructs the NFULA_PAYLOAD netlink
attribute using skb_put() and skb_copy_bits(), bypassing the standard
nla_reserve()/nla_put() helpers. While nla_total_size(data_len) bytes
are allocated (including NLA alignment padding), only data_len bytes
of actual packet data are copied. The trailing nla_padlen(data_len)
bytes (1-3 when data_len is not 4-byte aligned) are never initialized,
leaking stale heap contents to userspace via the NFLOG netlink socket.

Replace the manual attribute construction with nla_reserve(), which
handles the tailroom check, header setup, and padding zeroing via
__nla_reserve(). The subsequent skb_copy_bits() fills in the payload
data on top of the properly initialized attribute.

## Affected

- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < 7f3e5d72455936f42709116fabeca3bb216cda62`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < 21d8efda029948d3666b0db5afcc0d36c0984aae`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < fc961dd7272b5e4a462999635e44a4770d7f2482`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < a8365d1064ded323797c5e28e91070c52f44b76c`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < a2f6ff3444b663d6cfa63eadd61327a18592885a`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < c9f6c51d36482805ac3ffadb9663fe775a13e926`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < 7eff72968161fb8ddb26113344de3b92fb7d7ef5`
- `Linux >= df6fb868d6118686805c2fa566e213a8f31c8e4f < 52025ebaa29f4eb4ed8bf92ce83a68f24ab7fdf7`
- `Linux 2.6.24`

## Remediation

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