{"id":"CVE-2026-98135","title":"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's sectors_per_cluster field\nwith a range test that rejects 0x8…","summary":"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's sectors_per_cluster field\nwith a range test that rejects 0x8…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 7.1, < 7.2.7","linux_kernel = 7.3"],"patched":["linux_kernel 7.2.7"],"published":"2026-09-25","updated":"2026-10-08","sourceUpdated":"2026-10-08T18:11:39.340","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98135","references":[{"url":"https://git.kernel.org/stable/c/323751a604e7533fa473874d999371592a614207","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7524c3145a3bac92bebbc47a29c007f1d874c9b3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.001,"epssPercentile":0.00858,"ingestedAt":"2026-09-25T11:06:38.812Z","slug":"CVE-2026-98135","body":"## Overview\n\nIn 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's 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->cluster_size = vol->sector_size << 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 'int'\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.\n\n## Affected\n\n- `linux_kernel >= 7.1, < 7.2.7`\n- `linux_kernel = 7.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.2.7`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":218243,"id":"CVE-2026-98135","ts":1791485933085,"field":"cvss","old":null,"new":"5.5"},{"seq":218242,"id":"CVE-2026-98135","ts":1791485933085,"field":"severity","old":"none","new":"medium"}]}