exfat: validate cluster allocation bits of the allocation bitmap

{
  "id": "b961c713af55e53830bd6f9d14cc6ecc63fe7b32cdaac68869adac1d0f5f4a7a",
  "url": "https://osv.dev/vulnerability/CVE-2025-40307",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "exfat: validate cluster allocation bits of the allocation bitmap",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: exfat: validate cluster allocation bits of the allocation bitmap syzbot created an exfat image with cluster bits not set for the allocation bitmap. exfat-fs reads and uses the allocation bitmap without checking this. The problem is that if the start cluster of the allocation bitmap is 6, cluster 6 can be allocated when creating a directory with mkdir. exfat zeros out this cluster in exfat_mkdir, which can delete existing entries. This can reallocate the allocated entries. In addition, the allocation bitmap is also zeroed out, so cluster 6 can be reallocated. This patch adds exfat_test_bitmap_range to validate that clusters used for the allocation bitmap are correctly marked as in-use.",
    "evidence": "osv:CVE-2025-40307",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.183",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.148",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.58",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.17.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-40307",
      "aliases": [
        "CVE-2025-40307"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                {
                  "fixed": "87f827d53bd0688597bda63ae95908e2ad39bac0"
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                  "fixed": "67ce8034dc0278ddd88cad93d4218a945180dddd"
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                  "fixed": "6bc58b4c53795ab5fe00648344aa7d9d61175f90"
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                  "fixed": "13c1d24803d5b0446b3f6f0fdd67e07ac1fdc7bf"
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                  "fixed": "79c1587b6cda74deb0c86fc7ba194b92958c793c"
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              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40307.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
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                {
                  "introduced": "5.7.0"
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                {
                  "fixed": "6.1.183"
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            {
              "type": "ECOSYSTEM",
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                  "introduced": "6.2.0"
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                  "fixed": "6.12.58"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.13.0"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40307.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:46.200012796Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/13c1d24803d5b0446b3f6f0fdd67e07ac1fdc7bf",
        "https://git.kernel.org/stable/c/67ce8034dc0278ddd88cad93d4218a945180dddd",
        "https://git.kernel.org/stable/c/6bc58b4c53795ab5fe00648344aa7d9d61175f90",
        "https://git.kernel.org/stable/c/79c1587b6cda74deb0c86fc7ba194b92958c793c",
        "https://git.kernel.org/stable/c/87f827d53bd0688597bda63ae95908e2ad39bac0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40307.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40307",
        "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/2025/40xxx/CVE-2025-40307.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40307",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513969,
  "published_at": "2025-12-08T00:46:32.659+00:00"
}