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GHSA-MP33-36GG-V9H7

Vulnerability from github – Published: 2026-04-13 15:31 – Updated: 2026-07-14 15:31
VLAI
Details

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.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-31428"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-13T14:16:12Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD\n\n__build_packet_message() manually constructs the NFULA_PAYLOAD netlink\nattribute using skb_put() and skb_copy_bits(), bypassing the standard\nnla_reserve()/nla_put() helpers. While nla_total_size(data_len) bytes\nare allocated (including NLA alignment padding), only data_len bytes\nof actual packet data are copied. The trailing nla_padlen(data_len)\nbytes (1-3 when data_len is not 4-byte aligned) are never initialized,\nleaking stale heap contents to userspace via the NFLOG netlink socket.\n\nReplace the manual attribute construction with nla_reserve(), which\nhandles the tailroom check, header setup, and padding zeroing via\n__nla_reserve(). The subsequent skb_copy_bits() fills in the payload\ndata on top of the properly initialized attribute.",
  "id": "GHSA-mp33-36gg-v9h7",
  "modified": "2026-07-14T15:31:51Z",
  "published": "2026-04-13T15:31:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31428"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/21d8efda029948d3666b0db5afcc0d36c0984aae"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/52025ebaa29f4eb4ed8bf92ce83a68f24ab7fdf7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7eff72968161fb8ddb26113344de3b92fb7d7ef5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7f3e5d72455936f42709116fabeca3bb216cda62"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a2f6ff3444b663d6cfa63eadd61327a18592885a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a8365d1064ded323797c5e28e91070c52f44b76c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c9f6c51d36482805ac3ffadb9663fe775a13e926"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc961dd7272b5e4a462999635e44a4770d7f2482"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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