---
id: CVE-2026-64533
title: 'fs/ntfs3: validate lcns_follow in log_replay conversion'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fs/ntfs3: validate lcns_follow in log_replay conversion

  log_replay() converts DIR_PAGE_ENTRY_32 records into DIR_PAGE_ENTRY
  records when replaying version 0 restart ta…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    ca343a99806b4fc8e27c48f08be3445c5fcd1445
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    ddfc8683e1a627dbf1b83bacf8961443dd654258
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    57c071e2c4f30b9c6f5aacb6679aab1269fbae99
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    159f694d682e4215b3822ae31ed3a4631628fe55
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    7adb38279812c9c06b0e3fa7382f4d7887f3fa2d
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    32b9f8733feb241627fa5f564b1a99b5cae974c5
  - >-
    Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 <
    6a4c53a2e26a865565bd6a460961e8d6fcb32329
  - Linux 5.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:41:51.439492Z'
published: '2026-07-27'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:42:40.223Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64533'
references:
  - url: 'https://git.kernel.org/stable/c/ca343a99806b4fc8e27c48f08be3445c5fcd1445'
  - url: 'https://git.kernel.org/stable/c/ddfc8683e1a627dbf1b83bacf8961443dd654258'
  - url: 'https://git.kernel.org/stable/c/57c071e2c4f30b9c6f5aacb6679aab1269fbae99'
  - url: 'https://git.kernel.org/stable/c/159f694d682e4215b3822ae31ed3a4631628fe55'
  - url: 'https://git.kernel.org/stable/c/7adb38279812c9c06b0e3fa7382f4d7887f3fa2d'
  - url: 'https://git.kernel.org/stable/c/32b9f8733feb241627fa5f564b1a99b5cae974c5'
  - url: 'https://git.kernel.org/stable/c/6a4c53a2e26a865565bd6a460961e8d6fcb32329'
tags:
  - cve.org
epss: 0.00135
epssPercentile: 0.02637
ingestedAt: '2026-10-16T17:24:46.826Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: validate lcns_follow in log_replay conversion

log_replay() converts DIR_PAGE_ENTRY_32 records into DIR_PAGE_ENTRY
records when replaying version 0 restart tables.

During this conversion, the memmove() length is derived directly from
the on-disk lcns_follow field:

	memmove(&dp->vcn, &dp0->vcn_low,
		2 * sizeof(u64) +
				le32_to_cpu(dp->lcns_follow) * sizeof(u64));

check_rstbl() validates restart table structure, but does not constrain
per-entry lcns_follow values relative to the entry size. A malformed
filesystem image can provide an oversized lcns_follow value, causing
the conversion memmove() to access memory beyond the bounds of the
allocated restart table buffer.

The same field is later used to bound iteration over page_lcns[],
so validating lcns_follow during conversion also prevents downstream
out-of-bounds access from the same malformed metadata.

Compute the maximum valid lcns_follow from the already-validated
restart table entry size and reject entries that exceed this bound.
Reuse the existing t16/t32 scratch variables already declared in
log_replay() to avoid introducing new declarations.

[almaz.alexandrovich@paragon-software.com: fixed the conflicts]

## Affected

- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < ca343a99806b4fc8e27c48f08be3445c5fcd1445`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < ddfc8683e1a627dbf1b83bacf8961443dd654258`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 57c071e2c4f30b9c6f5aacb6679aab1269fbae99`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 159f694d682e4215b3822ae31ed3a4631628fe55`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 7adb38279812c9c06b0e3fa7382f4d7887f3fa2d`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 32b9f8733feb241627fa5f564b1a99b5cae974c5`
- `Linux >= b46acd6a6a627d876898e1c84d3f84902264b445 < 6a4c53a2e26a865565bd6a460961e8d6fcb32329`
- `Linux 5.15`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.