# CVE-2026-31716: fs/ntfs3: validate rec->used in journal-replay file record check

> A missing validation in the Linux kernel NTFS3 driver allows memory corruption via a crafted filesystem, potentially leading to code execution or system crashes.

- **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:** 1 May 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-31716, DEBIAN-CVE-2026-31716, GHSA-vw9p-6cf6-hxfh, ROOT-OS-DEBIAN-12-CVE-2026-31716, ROOT-OS-UBUNTU-2204-CVE-2026-31716, ROOT-OS-UBUNTU-2404-CVE-2026-31716, UBUNTU-CVE-2026-31716

## What is CVE-2026-31716?

CVE-2026-31716 is a high-severity memory corruption vulnerability in Linux kernel, published on 1 May 2026. 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: validate rec->used in journal-replay file record check

check_file_record() validates rec->total against the record size but
never validates rec->used.  The do_action() journal-replay handlers read
rec->used from disk and use it to compute memmove lengths:

  DeleteAttribute:    memmove(attr, ..., used - asize - roff)
  CreateAttribute:    memmove(..., attr, used - roff)
  change_attr_size:   memmove(..., used - PtrOffset(rec, next))

When rec->used is smaller than the offset of a validated attribute, or
larger than the record size, these subtractions can underflow allowing
us to copy huge amounts of memory in to a 4kb buffer, generally
considered a bad idea overall.

This requires a corrupted filesystem, which isn't a threat model the
kernel really needs to worry about, but checking for such an obvious
out-of-bounds value is good to keep things robust, especially on journal
replay

Fix this up by bounding rec->used correctly.

This is much like commit b2bc7c44ed17 ("fs/ntfs3: Fix slab-out-of-bounds
read in DeleteIndexEntryRoot") which checked different values in this
same switch statement.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-31716?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31716?

Apply the vendor's patch.

## Is CVE-2026-31716 being exploited?

There is no known exploitation of CVE-2026-31716 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31716 and fix it if it is affected.

What it is: CVE-2026-31716 is a high-severity memory corruption vulnerability in Linux kernel, published on 1 May 2026. 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-2026-31716 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-31716/ (Markdown: https://insights.sbomify.com/CVE-2026-31716/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31716
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31716
- OSV: https://osv.dev/vulnerability/CVE-2026-31716

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31716/
Summaries are generated and may contain mistakes; the official description above is the record.