Linux Kernel CVE-2026-72204

The Linux kernel's legacy ntfs driver handles NTFS filesystem structures including $INDEX_ROOT attributes, which store the root node of the B-tree index used for directory entries and named index lookups. Prior to this patch, root size and header geometry checks were implemented inconsistently: the validation logic applied when reading directory inodes differed from the path taken for named index inodes, creating a divergence that could allow a malformed $INDEX_ROOT structure to bypass sanity checks in one code path while being rejected in the other. The fix introduces a centralized validation helper called for both read paths, ensuring uniform rejection of malformed headers. CWE classification is listed as N/A in available data, so the precise root-cause class - whether improper input validation, integer overflow leading to undersized reads, or out-of-bounds access - is not formally confirmed. Affected version range per EUVD-2026-58962 spans from commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 through two separate stable-branch fix commits, indicating the flaw has been present since at least the initial kernel NTFS implementation.