---
id: CVE-2025-37750
title: 'smb: client: fix UAF in decryption with multichannel'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: fix UAF in decryption with multichannel

  After commit f7025d861694 ("smb: client: allocate crypto only for
  primary server") and commit b0abcd65ec54 ("smb: …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bce966530fd5542bbb422cb45ecb775f7a1a6bc3 <
    4e94c8cc7fa220ac50d6a3ce9a63d227696c95b8
  - >-
    Linux >= c8c6af46286a513769650935ff858fc67cf51a6d <
    08160de2a65227e5b64fcb6765cd936ec384ee93
  - >-
    Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a <
    aa5a1e4b882964eb79d5b5d1d1e8a1a5efbb1d15
  - >-
    Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a <
    e859b216d94668bc66330e61be201234f4413d1a
  - >-
    Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a <
    950557922c1298464749c216d8763e97faf5d0a6
  - >-
    Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a <
    9502dd5c7029902f4a425bf959917a5a9e7c0e50
  - Linux 8f14a476abba13144df5434871a7225fd29af633
  - Linux ef51c0d544b1518b35364480317ab6d3468f205d
  - Linux 0809fb86ad13b29e1d6d491364fc7ea4fb545995
  - Linux 538c26d9bf70c90edc460d18c81008a4e555925a
  - Linux >= 6.1.128 < 6.1.191
  - Linux >= 5.10.237 < 5.11
  - Linux >= 5.15.181 < 5.16
  - Linux >= 6.11.4 < 6.12
  - Linux 6.12
published: '2025-05-01'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T12:21:18.944Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-37750'
references:
  - url: 'https://git.kernel.org/stable/c/4e94c8cc7fa220ac50d6a3ce9a63d227696c95b8'
  - url: 'https://git.kernel.org/stable/c/08160de2a65227e5b64fcb6765cd936ec384ee93'
  - url: 'https://git.kernel.org/stable/c/aa5a1e4b882964eb79d5b5d1d1e8a1a5efbb1d15'
  - url: 'https://git.kernel.org/stable/c/e859b216d94668bc66330e61be201234f4413d1a'
  - url: 'https://git.kernel.org/stable/c/950557922c1298464749c216d8763e97faf5d0a6'
  - url: 'https://git.kernel.org/stable/c/9502dd5c7029902f4a425bf959917a5a9e7c0e50'
tags:
  - cve.org
epss: 0.00501
epssPercentile: 0.42894
ingestedAt: '2026-10-21T12:48:53.712Z'
---

## Overview

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

smb: client: fix UAF in decryption with multichannel

After commit f7025d861694 ("smb: client: allocate crypto only for
primary server") and commit b0abcd65ec54 ("smb: client: fix UAF in
async decryption"), the channels started reusing AEAD TFM from primary
channel to perform synchronous decryption, but that can't done as
there could be multiple cifsd threads (one per channel) simultaneously
accessing it to perform decryption.

This fixes the following KASAN splat when running fstest generic/249
with 'vers=3.1.1,multichannel,max_channels=4,seal' against Windows
Server 2022:

BUG: KASAN: slab-use-after-free in gf128mul_4k_lle+0xba/0x110
Read of size 8 at addr ffff8881046c18a0 by task cifsd/986
CPU: 3 UID: 0 PID: 986 Comm: cifsd Not tainted 6.15.0-rc1 #1
PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-3.fc41
04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x5d/0x80
 print_report+0x156/0x528
 ? gf128mul_4k_lle+0xba/0x110
 ? __virt_addr_valid+0x145/0x300
 ? __phys_addr+0x46/0x90
 ? gf128mul_4k_lle+0xba/0x110
 kasan_report+0xdf/0x1a0
 ? gf128mul_4k_lle+0xba/0x110
 gf128mul_4k_lle+0xba/0x110
 ghash_update+0x189/0x210
 shash_ahash_update+0x295/0x370
 ? __pfx_shash_ahash_update+0x10/0x10
 ? __pfx_shash_ahash_update+0x10/0x10
 ? __pfx_extract_iter_to_sg+0x10/0x10
 ? ___kmalloc_large_node+0x10e/0x180
 ? __asan_memset+0x23/0x50
 crypto_ahash_update+0x3c/0xc0
 gcm_hash_assoc_remain_continue+0x93/0xc0
 crypt_message+0xe09/0xec0 [cifs]
 ? __pfx_crypt_message+0x10/0x10 [cifs]
 ? _raw_spin_unlock+0x23/0x40
 ? __pfx_cifs_readv_from_socket+0x10/0x10 [cifs]
 decrypt_raw_data+0x229/0x380 [cifs]
 ? __pfx_decrypt_raw_data+0x10/0x10 [cifs]
 ? __pfx_cifs_read_iter_from_socket+0x10/0x10 [cifs]
 smb3_receive_transform+0x837/0xc80 [cifs]
 ? __pfx_smb3_receive_transform+0x10/0x10 [cifs]
 ? __pfx___might_resched+0x10/0x10
 ? __pfx_smb3_is_transform_hdr+0x10/0x10 [cifs]
 cifs_demultiplex_thread+0x692/0x1570 [cifs]
 ? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
 ? rcu_is_watching+0x20/0x50
 ? rcu_lockdep_current_cpu_online+0x62/0xb0
 ? find_held_lock+0x32/0x90
 ? kvm_sched_clock_read+0x11/0x20
 ? local_clock_noinstr+0xd/0xd0
 ? trace_irq_enable.constprop.0+0xa8/0xe0
 ? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
 kthread+0x1fe/0x380
 ? kthread+0x10f/0x380
 ? __pfx_kthread+0x10/0x10
 ? local_clock_noinstr+0xd/0xd0
 ? ret_from_fork+0x1b/0x60
 ? local_clock+0x15/0x30
 ? lock_release+0x29b/0x390
 ? rcu_is_watching+0x20/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x31/0x60
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

## Affected

- `Linux >= bce966530fd5542bbb422cb45ecb775f7a1a6bc3 < 4e94c8cc7fa220ac50d6a3ce9a63d227696c95b8`
- `Linux >= c8c6af46286a513769650935ff858fc67cf51a6d < 08160de2a65227e5b64fcb6765cd936ec384ee93`
- `Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a < aa5a1e4b882964eb79d5b5d1d1e8a1a5efbb1d15`
- `Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a < e859b216d94668bc66330e61be201234f4413d1a`
- `Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a < 950557922c1298464749c216d8763e97faf5d0a6`
- `Linux >= b0abcd65ec545701b8793e12bc27dc98042b151a < 9502dd5c7029902f4a425bf959917a5a9e7c0e50`
- `Linux 8f14a476abba13144df5434871a7225fd29af633`
- `Linux ef51c0d544b1518b35364480317ab6d3468f205d`
- `Linux 0809fb86ad13b29e1d6d491364fc7ea4fb545995`
- `Linux 538c26d9bf70c90edc460d18c81008a4e555925a`
- `Linux >= 6.1.128 < 6.1.191`
- `Linux >= 5.10.237 < 5.11`
- `Linux >= 5.15.181 < 5.16`
- `Linux >= 6.11.4 < 6.12`
- `Linux 6.12`

## Remediation

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