---
id: CVE-2026-64296
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  exfat: bound uniname advance in exfat_find_dir_entry()

  In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the
  output pointer by a fixed amount whil…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  exfat: bound uniname advance in exfat_find_dir_entry()

  In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the
  output pointer by a fixed amount whil…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
published: '2026-07-25'
updated: '2026-07-27'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64296'
references:
  - url: 'https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00169
epssPercentile: 0.06589
ingestedAt: '2026-07-27T06:16:50.168Z'
---

## Overview

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

exfat: bound uniname advance in exfat_find_dir_entry()

In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the
output pointer by a fixed amount while the loop guard only tracks the
accumulated name length:

	if (++order == 2)
		uniname = p_uniname->name;
	else
		uniname += EXFAT_FILE_NAME_LEN;
	len = exfat_extract_uni_name(ep, entry_uniname);
	name_len += len;
	unichar = *(uniname+len);
	*(uniname+len) = 0x0;

uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len
grows only by the actual extracted length, which is shorter when a name
fragment contains an early NUL.  The only guard is
`name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short
name fragments lets uniname run far past the
p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small,
causing an out-of-bounds read and write at *(uniname+len).

The sibling extractor exfat_get_uniname_from_ext_entry() already stops
on a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard
added in commit d42334578eba ("exfat: check if filename entries exceeds
max filename length")); exfat_find_dir_entry() never got the
equivalent.  Track the per-entry write offset as a count and reject a
fragment once the offset, or the offset plus the extracted length, would
exceed MAX_NAME_LENGTH, before forming the output pointer.

## Remediation

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