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netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.253, 5.15.203, 6.1.167, 6.12.78, 6.18.20, 6.19.10, 6.6.130
CVEs
CVE-2026-23456
Confirmed fixed CVEs
Not specified
Updated in this feed
6 Nov 2026, 01:42 UTC · Revision 1

Source evidence

netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case

core-osv · Original source

Published 3 Apr 2026, 15:15 UTC

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().

osv:CVE-2026-23456

Kernel

Fixed versions: 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

Complete source record
{
  "id": "33a07dcd89805b754552aafa360e8de2054e0441e211c805d96fad7c90f2971b",
  "url": "https://osv.dev/vulnerability/CVE-2026-23456",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().",
    "evidence": "osv:CVE-2026-23456",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.10.253",
            "evidence": "/affected/1/ranges"
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          {
            "value": "5.15.203",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.167",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.6.130",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.78",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.20",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
          }
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        "affected_versions": []
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    "severity": "high",
    "structured": {
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      "aliases": [
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H"
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      "affected": [
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        {
          "ranges": [
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                  "introduced": "2.6.17"
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                  "introduced": "5.11.0"
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            {
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                  "introduced": "5.16.0"
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            {
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            {
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23456.json"
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      ],
      "modified": "2026-10-28T02:30:45.891294666Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a",
        "https://git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d",
        "https://git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20",
        "https://git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb",
        "https://git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2",
        "https://git.kernel.org/stable/c/a2cd54b9348e485d338b3c132338a4410c99afaf",
        "https://git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7",
        "https://git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23456.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23456",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23456.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-23456",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513964,
  "published_at": "2026-04-03T15:15:37.534+00:00"
}