# CVE-2026-64532: fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation}

> A missing bounds check in the Linux kernel NTFS3 driver allows out-of-bounds writes via crafted disk images, potentially leading to code execution or 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:** 27 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-93971, BELL-CVE-2026-64532, DEBIAN-CVE-2026-64532, GHSA-4mf8-7864-ff29, ROOT-OS-DEBIAN-12-CVE-2026-64532, UBUNTU-CVE-2026-64532

## What is CVE-2026-64532?

CVE-2026-64532 is a high-severity memory corruption vulnerability in Linux, published on 27 Jul 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: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation}

In do_action()'s UpdateRecordDataRoot (fslog.c:3489) and
UpdateRecordDataAllocation (fslog.c:3697) cases, the memmove
destination is `Add2Ptr(e, le16_to_cpu(e->view.data_off))`,
where e->view.data_off comes from an on-disk NTFS_DE inside
an INDEX_ROOT or INDEX_BUFFER.  Neither case validates
view.data_off + dlen against e->size; the existing
check_if_index_root / check_if_alloc_index helpers walk the
entry chain and validate the entry's offset, but not its
internal view fields.

The neighbouring read sites (e.g., fs/ntfs3/index.c when
iterating view entries) check view.data_off + view.data_size
<= e->size.  Apply the same bound at the two memmove sites.

Reproduced under UML+KASAN on mainline 8d90b09e6741 via
pr_warn-only probe instrumentation: with view.data_off forced
to 0xFFFC, the memmove writes 32 bytes past the end of the
NTFS_DE.

This is similar in shape to Pavitra Jha's 2026-05-02 patch
"fs/ntfs3: prevent oob in case UpdateRecordDataRoot"
(<20260502105008.21827-1-jhapavitra98@gmail.com>) which
proposes calling ntfs3_bad_de_range(); that helper does not
exist in mainline.  This patch uses inline checks.

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

## Which versions are affected by CVE-2026-64532?


## How do I fix CVE-2026-64532?

Apply the vendor's patch.

## Is CVE-2026-64532 being exploited?

There is no known exploitation of CVE-2026-64532 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64532 and fix it if it is affected.

What it is: CVE-2026-64532 is a high-severity memory corruption vulnerability in Linux, published on 27 Jul 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-2026-64532 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-2026-64532/ (Markdown: https://insights.sbomify.com/CVE-2026-64532/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64532
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64532
- OSV: https://osv.dev/vulnerability/CVE-2026-64532

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64532/
Summaries are generated and may contain mistakes; the official description above is the record.