CVE-2025-40307 (GCVE-0-2025-40307)
Vulnerability from cvelistv5
Published
2025-12-08 00:46
Modified
2025-12-20 08:51
Severity ?
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1acf1a564b6034b5af1e7fb23cb98cb3bb4f6003
Version: 1acf1a564b6034b5af1e7fb23cb98cb3bb4f6003
Version: 1acf1a564b6034b5af1e7fb23cb98cb3bb4f6003
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/exfat/balloc.c"
          ],
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          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "versionType": "original_commit_for_fix"
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: validate cluster allocation bits of the allocation bitmap\n\nsyzbot created an exfat image with cluster bits not set for the allocation\nbitmap. exfat-fs reads and uses the allocation bitmap without checking\nthis. The problem is that if the start cluster of the allocation bitmap\nis 6, cluster 6 can be allocated when creating a directory with mkdir.\nexfat zeros out this cluster in exfat_mkdir, which can delete existing\nentries. This can reallocate the allocated entries. In addition,\nthe allocation bitmap is also zeroed out, so cluster 6 can be reallocated.\nThis patch adds exfat_test_bitmap_range to validate that clusters used for\nthe allocation bitmap are correctly marked as in-use."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-20T08:51:58.576Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/6bc58b4c53795ab5fe00648344aa7d9d61175f90"
        },
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          "url": "https://git.kernel.org/stable/c/13c1d24803d5b0446b3f6f0fdd67e07ac1fdc7bf"
        },
        {
          "url": "https://git.kernel.org/stable/c/79c1587b6cda74deb0c86fc7ba194b92958c793c"
        }
      ],
      "title": "exfat: validate cluster allocation bits of the allocation bitmap",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40307",
    "datePublished": "2025-12-08T00:46:32.659Z",
    "dateReserved": "2025-04-16T07:20:57.185Z",
    "dateUpdated": "2025-12-20T08:51:58.576Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40307\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-08T01:16:02.950\",\"lastModified\":\"2025-12-08T18:26:19.900\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nexfat: validate cluster allocation bits of the allocation bitmap\\n\\nsyzbot created an exfat image with cluster bits not set for the allocation\\nbitmap. exfat-fs reads and uses the allocation bitmap without checking\\nthis. The problem is that if the start cluster of the allocation bitmap\\nis 6, cluster 6 can be allocated when creating a directory with mkdir.\\nexfat zeros out this cluster in exfat_mkdir, which can delete existing\\nentries. This can reallocate the allocated entries. In addition,\\nthe allocation bitmap is also zeroed out, so cluster 6 can be reallocated.\\nThis patch adds exfat_test_bitmap_range to validate that clusters used for\\nthe allocation bitmap are correctly marked as in-use.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/13c1d24803d5b0446b3f6f0fdd67e07ac1fdc7bf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6bc58b4c53795ab5fe00648344aa7d9d61175f90\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/79c1587b6cda74deb0c86fc7ba194b92958c793c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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