# CVE-2025-40068: fs: ntfs3: Fix integer overflow in run_unpack()

> An integer overflow in the Linux kernel NTFS3 driver allows attackers to read or destroy arbitrary disk data by manipulating MFT records.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 28 Oct 2025
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-68933, BELL-CVE-2025-40068, DEBIAN-CVE-2025-40068, GHSA-gv9m-p4c7-mxp3, ROOT-OS-DEBIAN-12-CVE-2025-40068, ROOT-OS-DEBIAN-13-CVE-2025-40068, ROOT-OS-UBUNTU-2204-CVE-2025-40068, ROOT-OS-UBUNTU-2404-CVE-2025-40068, UBUNTU-CVE-2025-40068

## What is CVE-2025-40068?

CVE-2025-40068 is a high-severity vulnerability in Linux, published on 28 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

fs: ntfs3: Fix integer overflow in run_unpack()

The MFT record relative to the file being opened contains its runlist,
an array containing information about the file's location on the physical
disk. Analysis of all Call Stack paths showed that the values of the
runlist array, from which LCNs are calculated, are not validated before
run_unpack function.

The run_unpack function decodes the compressed runlist data format
from MFT attributes (for example, $DATA), converting them into a runs_tree
structure, which describes the mapping of virtual clusters (VCN) to
logical clusters (LCN). The NTFS3 subsystem also has a shortcut for
deleting files from MFT records - in this case, the RUN_DEALLOCATE
command is sent to the run_unpack input, and the function logic
provides that all data transferred to the runlist about file or
directory is deleted without creating a runs_tree structure.

Substituting the runlist in the $DATA attribute of the MFT record for an
arbitrary file can lead either to access to arbitrary data on the disk
bypassing access checks to them (since the inode access check
occurs above) or to destruction of arbitrary data on the disk.

Add overflow check for addition operation.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

## Which versions are affected by CVE-2025-40068?


## How do I fix CVE-2025-40068?

Apply the vendor's patch.

## Is CVE-2025-40068 being exploited?

There is no known exploitation of CVE-2025-40068 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40068 and fix it if it is affected.

What it is: CVE-2025-40068 is a high-severity vulnerability in Linux, published on 28 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-40068 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-2025-40068/ (Markdown: https://insights.sbomify.com/CVE-2025-40068/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40068
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40068
- OSV: https://osv.dev/vulnerability/CVE-2025-40068

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40068/
Summaries are generated and may contain mistakes; the official description above is the record.