CVE-2026-98135
Received
Received - Intake
NTFS Boot Sector Validation Flaw in Linux Kernel
Vulnerability report for CVE-2026-98135, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-25
Last updated on: 2026-09-25
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
