CVE-2025-40067 fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist
A malformed NTFS image can cause a denial of service in the Linux kernel NTFS3 driver during rename operations due to improper bitmap validation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-40067?
CVE-2025-40067 is a high-severity denial of service vulnerability in Linux, published on 28 Oct 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2025-40067?
How do I fix CVE-2025-40067?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-40067 being exploited?
There is no known exploitation of CVE-2025-40067 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40067, DEBIAN-CVE-2025-40067, GHSA-rxpf-8w5h-7fch, ROOT-OS-DEBIAN-13-CVE-2025-40067, UBUNTU-CVE-2025-40067.