CVE-2026-98136: ntfs: bound $AttrDef table walk to the loaded table size

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-10-19
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: ntfs: bound $AttrDef table walk to the loaded table size ntfs_attr_find_in_attrdef() walks the in-memory $AttrDef table, but the loop condition bounds only the start of each entry, not the whole entry: for (ad = vol->attrdef; (u8 *)ad - (u8 *)vol->attrdef < vol->attrdef_size && ad->type; ++ad) struct attr_def is 160 bytes; the guard reads ad->type at offset 128 and the loop body reads further fields. vol->attrdef is kvzalloc(i_size), where i_size is the on-disk $AttrDef data size, checked in load_and_init_attrdef() only as 0 < i_size <= 0x7fffffff. A volume whose $AttrDef data size is smaller than one entry (e.g. 120 bytes) makes the read of ad->type run past the allocation. Creating a file reaches this through ntfs_attr_size_bounds_check() and reads out of bounds: BUG: KASAN: slab-out-of-bounds in ntfs_attr_find_in_attrdef+0x66/0xa0 Read of size 4 at addr ffff888005833280 by task init/1 ntfs_attr_find_in_attrdef ntfs_attr_size_bounds_check ntfs_attr_can_be_non_resident ntfs_attr_add Require the whole entry to lie within attrdef_size in the loop guard, and reject at mount a $AttrDef too small to hold one attr_def entry.

Affected products

Linux kernel: from 7.1 before 7.2.7; 7.3-rc1 — fixed in 7.2.7

How to fix

Upgrade to a fixed version: Linux kernel 7.2.7. Check the vendor advisory for mitigations.

References

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