FKIE_CVE-2026-98135

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 11:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs: reject invalid sectors_per_cluster in the boot sector is_boot_sector_ntfs() checks the boot sector's sectors_per_cluster field with a range test that rejects 0x81..0xf3 but accepts 0 and other non-power-of-two counts. A zero value reaches parse_ntfs_boot_sector(): sectors_per_cluster_bits = ffs(sectors_per_cluster) - 1; ... vol->cluster_size = vol->sector_size << sectors_per_cluster_bits; ffs(0) is 0, so sectors_per_cluster_bits becomes (unsigned)-1 and the shift is undefined: UBSAN: shift-out-of-bounds in fs/ntfs/super.c:673:39 shift exponent 4294967295 is too large for 32-bit type 'int' This change rejects any non-power-of-two value, since it feeds the aforementioned shift via ffs() - 1, which only yields the correct shift for a power of two.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/323751a604e7533fa473874d999371592a614207
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7524c3145a3bac92bebbc47a29c007f1d874c9b3
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7524c3145a3bac92bebbc47a29c007f1d874c9b3",
              "status": "affected",
              "version": "6251f0b0de7d645e3591931ca4c11d8322c1866f",
              "versionType": "git"
            },
            {
              "lessThan": "323751a604e7533fa473874d999371592a614207",
              "status": "affected",
              "version": "6251f0b0de7d645e3591931ca4c11d8322c1866f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: reject invalid sectors_per_cluster in the boot sector\n\nis_boot_sector_ntfs() checks the boot sector\u0027s sectors_per_cluster field\nwith a range test that rejects 0x81..0xf3 but accepts 0 and other\nnon-power-of-two counts. A zero value reaches parse_ntfs_boot_sector():\n\n\tsectors_per_cluster_bits = ffs(sectors_per_cluster) - 1;\n\t...\n\tvol-\u003ecluster_size = vol-\u003esector_size \u003c\u003c sectors_per_cluster_bits;\n\nffs(0) is 0, so sectors_per_cluster_bits becomes (unsigned)-1 and the\nshift is undefined:\n\n  UBSAN: shift-out-of-bounds in fs/ntfs/super.c:673:39\n  shift exponent 4294967295 is too large for 32-bit type \u0027int\u0027\n\nThis change rejects any non-power-of-two value, since it feeds the\naforementioned shift via ffs() - 1, which only yields the correct shift for a\npower of two."
    }
  ],
  "id": "CVE-2026-98135",
  "lastModified": "2026-09-25T11:17:44.933",
  "metrics": {},
  "published": "2026-09-25T11:17:44.933",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/323751a604e7533fa473874d999371592a614207"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7524c3145a3bac92bebbc47a29c007f1d874c9b3"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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