# CVE-2026-80869: ntfs: bound the attribute-list entry in ntfs_read_inode_mount()

> A crafted NTFS image can cause an out-of-bounds read in the Linux kernel during mount, potentially disclosing memory contents to local attackers.

- **Severity:** Not scored
- **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:** 4 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-80869, GHSA-3w59-j737-r4rc, UBUNTU-CVE-2026-80869

## What is CVE-2026-80869?

CVE-2026-80869 is a vulnerability in Linux, published on 4 Sep 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:

ntfs: bound the attribute-list entry in ntfs_read_inode_mount()

The $MFT attribute-list walk in ntfs_read_inode_mount() validates each
entry only with "(u8 *)al_entry + 6 > al_end" and
"(u8 *)al_entry + le16_to_cpu(al_entry->length) > al_end", but then reads
al_entry->lowest_vcn (an __le64 at offset 8) and al_entry->mft_reference
(offset 16) -- fields beyond the 6 bytes proven in range. al_entry->length
is attacker-controlled and only required non-zero, so a short entry (e.g.
length 8) placed at the tail passes both checks while the lowest_vcn /
mft_reference reads fall past al_end.

al_end is ni->attr_list + attr_list_size (the on-disk size); the buffer is
kvzalloc(round_up(attr_list_size, SECTOR_SIZE)), so the sector rounding
usually absorbs the over-read -- but when attr_list_size is a multiple of
SECTOR_SIZE there is no slack and a crafted $MFT attribute list produces an
out-of-bounds read at mount time.

Validate the entry with ntfs_attr_list_entry_is_valid() (added in patch
1/3) before dereferencing it, matching the bound the other attribute-list
walks now use. The validator already requires the length to cover the fixed
header, which makes the separate "!al_entry->length" check redundant, so
drop it too.

## Which versions are affected by CVE-2026-80869?


## How do I fix CVE-2026-80869?

Apply the vendor's patch.

## Is CVE-2026-80869 being exploited?

There is no known exploitation of CVE-2026-80869 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80869 and fix it if it is affected.

What it is: CVE-2026-80869 is a vulnerability in Linux, published on 4 Sep 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-2026-80869 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-2026-80869/ (Markdown: https://insights.sbomify.com/CVE-2026-80869/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80869
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80869
- OSV: https://osv.dev/vulnerability/CVE-2026-80869

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80869/
Summaries are generated and may contain mistakes; the official description above is the record.