---
id: CVE-2026-93787
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: bound dirent name against end of SMB response in cifs_filldir

  cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST /
  FIND_NEXT response u…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: bound dirent name against end of SMB response in cifs_filldir

  cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST /
  FIND_NEXT response u…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6e3b965267b7313903baba2739992b1e2e92d540
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    03003506c86f90312b0966283662c42fcab66e4b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6
  - Linux < 6.12.111
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-09-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T05:17:02.540'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93787'
references:
  - url: 'https://git.kernel.org/stable/c/03003506c86f90312b0966283662c42fcab66e4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6e3b965267b7313903baba2739992b1e2e92d540'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T16:47:15.903Z'
---

## Overview

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

smb: client: bound dirent name against end of SMB response in cifs_filldir

cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST /
FIND_NEXT response using a length (de.namelen) supplied by the server.
The kmalloc'd SMB response buffer is bounded, but nothing checks that
de.name + de.namelen still lies inside that buffer before the eventual
filldir64() -> verify_dirent_name() -> memchr() reads namelen bytes.

A hostile SMB1 server that returns an oversized FileNameLength in a
directory entry therefore causes memchr() to read past the end of the
response slab buffer. Reachable from any user who can list a directory
on a CIFS mount served by an attacker-controlled server (getdents64()
on the mounted directory):

  BUG: KASAN: slab-out-of-bounds in memchr+0x71/0x80
  Read of size 1 at addr ffff88800e0640cc by task poc/115
  Call Trace:
   dump_stack_lvl+0x64/0x80
   print_report+0xce/0x620
   kasan_report+0xec/0x120
   memchr+0x71/0x80
   filldir64+0x4c/0x6a0
   cifs_filldir.constprop.0+0x9bb/0x1e00
   cifs_readdir+0x2101/0x3380
   iterate_dir+0x19c/0x520
   __x64_sys_getdents64+0x126/0x210
   do_syscall_64+0x107/0x5a0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

Pass the end-of-response pointer down to cifs_filldir() and reject
entries whose name would extend past that boundary.

This bug was discovered by Artiphishell's vTriage pipeline, which
generated a userspace reproducer (an emulated hostile SMB1 server plus
a getdents64() client) that reliably triggers the KASAN report on an
unpatched kernel. The fix below was drafted with the Claude coding
assistant; a userspace reproducer is available on request.

## Remediation

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