# CVE-2026-89781: fs/ntfs3: fix out-of-bounds read in read_log_rec_buf()

> A crafted NTFS image triggers an out-of-bounds read in the Linux kernel NTFS3 driver, potentially leaking memory or causing a crash.

- **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:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101192, BELL-CVE-2026-89781, DEBIAN-CVE-2026-89781, GHSA-xf98-5fqf-rh4f, UBUNTU-CVE-2026-89781

## What is CVE-2026-89781?

CVE-2026-89781 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 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: fix out-of-bounds read in read_log_rec_buf()

read_log_rec_buf() copies a log record into a caller buffer starting at

	u32 off = lsn_to_page_off(log, lsn) + log->record_header_len;

log->record_header_len (and log->data_off, used for the following pages)
comes verbatim from the on-disk restart area and is only checked for
8-byte alignment in is_rst_area_valid(), so off can exceed
log->page_size. "tail = log->page_size - off" then underflows and
memcpy() reads past the page_size-sized buffer returned by
read_log_page(), spilling adjacent slab memory into the replay buffer.

This is reachable by mounting a crafted NTFS image:

 BUG: KASAN: slab-out-of-bounds in read_log_rec_buf+0x216/0x580
 Read of size 64 at addr ffff88800a877ff8 by task exploit/127
  read_log_rec_buf fs/ntfs3/fslog.c:2299
  log_replay fs/ntfs3/fslog.c:4216
  ntfs_loadlog_and_replay fs/ntfs3/fsntfs.c:324
  ntfs_fill_super fs/ntfs3/super.c:1392
  get_tree_bdev_flags fs/super.c:1694
  __x64_sys_mount fs/namespace.c:4360
 The buggy address is located 4088 bytes to the right of
 the 4096-byte region [ffff88800a876000, ffff88800a877000)

Reject an in-page offset outside the current page before the copy.

[almaz.alexandrovich@paragon-software.com: replaced the >= sign with >]

## Which versions are affected by CVE-2026-89781?


## How do I fix CVE-2026-89781?

Apply the vendor's patch.

## Is CVE-2026-89781 being exploited?

There is no known exploitation of CVE-2026-89781 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89781 and fix it if it is affected.

What it is: CVE-2026-89781 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 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-2026-89781 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-2026-89781/ (Markdown: https://insights.sbomify.com/CVE-2026-89781/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89781
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89781
- OSV: https://osv.dev/vulnerability/CVE-2026-89781

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89781/
Summaries are generated and may contain mistakes; the official description above is the record.