CVE-2025-40067: fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-28 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist Index allocation requires at least one bit in the $BITMAP attribute to track usage of index entries. If the bitmap is empty while index blocks are already present, this reflects on-disk corruption. syzbot triggered this condition using a malformed NTFS image. During a rename() operation involving a long filename (which spans multiple index entries), the empty bitmap allowed the name to be added without valid tracking. Subsequent deletion of the original entry failed with -ENOENT, due to unexpected index state. Reject such cases by verifying that the bitmap is not empty when index blocks exist.

Affected products

Linux: from 6.6.102 before 6.6.112; from 6.12.42 before 6.12.53; from 6.15.10 before 6.16; from 6.16.1 before 6.17 — fixed in 6.6.112, 6.12.53, 6.16, 6.17

How to fix

Upgrade to a fixed version: Linux 6.6.112, 6.12.53, 6.16, 6.17. Check the vendor advisory for mitigations.

References

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