udf: validate VAT header length against the VAT inode size

{
  "id": "3221fa2c6a33daa560e00d19bf043de4fd9b1734e9bb9e907690b421f4ef80a5",
  "url": "https://osv.dev/vulnerability/CVE-2026-64323",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "udf: validate VAT header length against the VAT inode size",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: udf: validate VAT header length against the VAT inode size udf_load_vat() takes the virtual partition's start offset straight from the on-disk VAT 2.0 header without checking it against the VAT inode size: map->s_type_specific.s_virtual.s_start_offset = le16_to_cpu(vat20->lengthHeader); map->s_type_specific.s_virtual.s_num_entries = (sbi->s_vat_inode->i_size - map->s_type_specific.s_virtual.s_start_offset) >> 2; lengthHeader is a fully attacker-controlled 16-bit value. If it exceeds the VAT inode size, the s_num_entries subtraction underflows to a huge count, which defeats the \"block > s_num_entries\" bound in udf_get_pblock_virt15(); and on the ICB-inline path that function reads ((__le32 *)(iinfo->i_data + s_start_offset))[block] so a large s_start_offset indexes past the inode's in-ICB data. Mounting a crafted UDF image with a virtual (VAT) partition then triggers an out-of-bounds read. Reject a VAT whose header length does not leave room for at least one entry within the VAT inode.",
    "evidence": "osv:CVE-2026-64323",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.261",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
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        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-64323",
      "aliases": [
        "CVE-2026-64323"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H"
        }
      ],
      "affected": [
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                {
                  "fixed": "883962731420ec271ed8c1cd76524f4b17faa982"
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                {
                  "fixed": "2900e02a0dd4fc30ac9840e7ce4ca0b041ab0d63"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64323.json"
          }
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        {
          "ranges": [
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "2.6.26"
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:51.526668847Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0ad2d09a8d66fa8dc6f9b70d660b5fb4478ea934",
        "https://git.kernel.org/stable/c/2900e02a0dd4fc30ac9840e7ce4ca0b041ab0d63",
        "https://git.kernel.org/stable/c/55287a3555ff0515b3aff181d2c08c0462a41709",
        "https://git.kernel.org/stable/c/74580fdf022909e184223cacc364feb826982d96",
        "https://git.kernel.org/stable/c/883962731420ec271ed8c1cd76524f4b17faa982",
        "https://git.kernel.org/stable/c/bb0d384c1f42a5b7ace0bd88fee80b9bb1d49acb",
        "https://git.kernel.org/stable/c/d8202786b3d75125c84ebc4de6d946f92fde0ee8",
        "https://git.kernel.org/stable/c/e610fb113cdfa8bf4247c9bf4f2337b81ad4ddad",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64323.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64323",
        "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/2026/64xxx/CVE-2026-64323.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64323",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 520406,
  "published_at": "2026-07-25T08:49:51.097+00:00"
}