# 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.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 28 Oct 2025
- **Updated:** 5 Aug 2026
- **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

## 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.

## Is CVE-2025-40067 being exploited?

There is no known exploitation of CVE-2025-40067 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40067 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-40067 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40067/ (Markdown: https://insights.sbomify.com/CVE-2025-40067/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40067
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40067
- OSV: https://osv.dev/vulnerability/CVE-2025-40067

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40067/
Summaries are generated and may contain mistakes; the official description above is the record.