# CVE-2026-72197: fs/ntfs3: bound DeleteIndexEntryAllocation memmove length

> A missing bounds check in the Linux kernel NTFS3 driver allows a crafted image to cause a kernel oops via an integer overflow in memmove.

- **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:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-72197, DEBIAN-CVE-2026-72197, GHSA-j9fv-qm2v-gr26, UBUNTU-CVE-2026-72197

## What is CVE-2026-72197?

CVE-2026-72197 is a high-severity vulnerability in Linux, published on 15 Aug 2026. 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: bound DeleteIndexEntryAllocation memmove length

In do_action()'s DeleteIndexEntryAllocation case, e->size comes
from an on-disk INDEX_BUFFER entry.  When e->size makes
e + e->size point past hdr + hdr->used,
PtrOffset(e1, Add2Ptr(hdr, used)) returns a negative ptrdiff_t
that is silently cast to a quasi-infinite size_t when passed
to memmove().  The memmove then walks past the destination
buffer.

The sibling DeleteIndexEntryRoot case at fslog.c:3540-3543
already carries the corresponding guard:

	if (PtrOffset(e1, Add2Ptr(hdr, used)) < esize ||
	    Add2Ptr(e, esize) > Add2Ptr(lrh, rec_len) ||
	    used + esize > le32_to_cpu(hdr->total)) {
		goto dirty_vol;
	}

Apply the same shape to the allocation-path case.  Also reject
esize == 0: memmove(e, e, ...) is a no-op and leaves
hdr->used unchanged, hiding a malformed entry from the
existing check_index_header() walk.

Reproduced under UML+KASAN on mainline 8d90b09e6741 by
mounting a crafted NTFS image: the unguarded memmove takes a
length of 0xffffffffffffff00 and the kernel oopses in
memmove+0x81/0x1a0 on the do_action+0x36a2 frame.

[almaz.alexandrovich@paragon-software.com: clang-formatted the changes]

## Which versions are affected by CVE-2026-72197?


## How do I fix CVE-2026-72197?

Apply the vendor's patch.

## Is CVE-2026-72197 being exploited?

There is no known exploitation of CVE-2026-72197 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72197 and fix it if it is affected.

What it is: CVE-2026-72197 is a high-severity vulnerability in Linux, published on 15 Aug 2026. 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-2026-72197 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-2026-72197/ (Markdown: https://insights.sbomify.com/CVE-2026-72197/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72197
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72197
- OSV: https://osv.dev/vulnerability/CVE-2026-72197

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72197/
Summaries are generated and may contain mistakes; the official description above is the record.