GHSA-RJQR-92W7-GFG4

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

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.

Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64323"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:13Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nudf: validate VAT header length against the VAT inode size\n\nudf_load_vat() takes the virtual partition\u0027s start offset straight from\nthe on-disk VAT 2.0 header without checking it against the VAT inode\nsize:\n\n\tmap-\u003es_type_specific.s_virtual.s_start_offset =\n\t\tle16_to_cpu(vat20-\u003elengthHeader);\n\tmap-\u003es_type_specific.s_virtual.s_num_entries =\n\t\t(sbi-\u003es_vat_inode-\u003ei_size -\n\t\t\tmap-\u003es_type_specific.s_virtual.s_start_offset) \u003e\u003e 2;\n\nlengthHeader is a fully attacker-controlled 16-bit value.  If it exceeds\nthe VAT inode size, the s_num_entries subtraction underflows to a huge\ncount, which defeats the \"block \u003e s_num_entries\" bound in\nudf_get_pblock_virt15(); and on the ICB-inline path that function reads\n\n\t((__le32 *)(iinfo-\u003ei_data + s_start_offset))[block]\n\nso a large s_start_offset indexes past the inode\u0027s in-ICB data.  Mounting\na crafted UDF image with a virtual (VAT) partition then triggers an\nout-of-bounds read.\n\nReject a VAT whose header length does not leave room for at least one\nentry within the VAT inode.",
  "id": "GHSA-rjqr-92w7-gfg4",
  "modified": "2026-07-27T06:30:33Z",
  "published": "2026-07-25T12:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64323"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0ad2d09a8d66fa8dc6f9b70d660b5fb4478ea934"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2900e02a0dd4fc30ac9840e7ce4ca0b041ab0d63"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/55287a3555ff0515b3aff181d2c08c0462a41709"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/74580fdf022909e184223cacc364feb826982d96"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/883962731420ec271ed8c1cd76524f4b17faa982"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb0d384c1f42a5b7ace0bd88fee80b9bb1d49acb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d8202786b3d75125c84ebc4de6d946f92fde0ee8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e610fb113cdfa8bf4247c9bf4f2337b81ad4ddad"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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