The Linux kernel NTFS driver incorrectly validates the sectors_per_cluster field in an NTFS boot sector. When the field is zero or non‑power‑of‑two, the computation ffs(sectors_per_cluster) – 1 evaluates to –1, causing an unsigned shift by an extremely large exponent. This undefined shift triggers a kernel panic, as evidenced by the UBSAN message about a shift-out-of-bounds error. No privilege escalation or arbitrary code execution is described in the advisory.

All Linux kernel builds that include the NTFS filesystem module and have not applied the change to reject invalid sector counts are affected. The advisory lists the kernel in general, including version 7.3 rc1, indicating that any kernel version parsing NTFS boot sectors before this patch is potentially impacted.

The CVSS score of 5.5 reflects medium severity. The EPSS score is below 1 %, indicating a very low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Based on the description, a malicious NTFS volume must be presented to the kernel (e.g., by mounting a crafted partition) to trigger the error, so the likely attack vector is local or privileged; remote exploitation is not indicated.