# CVE-2023-52572: cifs: Fix UAF in cifs_demultiplex_thread()

> A use-after-free vulnerability in the Linux kernel CIFS module allows attackers to cause a denial of service or potentially execute code.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Mar 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-54137, BELL-CVE-2023-52572, CLSA-2025-1755707175, CLSA-2025-1755707619, DEBIAN-CVE-2023-52572, GHSA-rj62-x3fp-f44h, ROOT-OS-UBUNTU-2204-CVE-2023-52572, UBUNTU-CVE-2023-52572

## What is CVE-2023-52572?

CVE-2023-52572 is a high-severity use after free vulnerability in Debian Debian Linux, published on 2 Mar 2024. 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:

cifs: Fix UAF in cifs_demultiplex_thread()

There is a UAF when xfstests on cifs:

  BUG: KASAN: use-after-free in smb2_is_network_name_deleted+0x27/0x160
  Read of size 4 at addr ffff88810103fc08 by task cifsd/923

  CPU: 1 PID: 923 Comm: cifsd Not tainted 6.1.0-rc4+ #45
  ...
  Call Trace:
   <TASK>
   dump_stack_lvl+0x34/0x44
   print_report+0x171/0x472
   kasan_report+0xad/0x130
   kasan_check_range+0x145/0x1a0
   smb2_is_network_name_deleted+0x27/0x160
   cifs_demultiplex_thread.cold+0x172/0x5a4
   kthread+0x165/0x1a0
   ret_from_fork+0x1f/0x30
   </TASK>

  Allocated by task 923:
   kasan_save_stack+0x1e/0x40
   kasan_set_track+0x21/0x30
   __kasan_slab_alloc+0x54/0x60
   kmem_cache_alloc+0x147/0x320
   mempool_alloc+0xe1/0x260
   cifs_small_buf_get+0x24/0x60
   allocate_buffers+0xa1/0x1c0
   cifs_demultiplex_thread+0x199/0x10d0
   kthread+0x165/0x1a0
   ret_from_fork+0x1f/0x30

  Freed by task 921:
   kasan_save_stack+0x1e/0x40
   kasan_set_track+0x21/0x30
   kasan_save_free_info+0x2a/0x40
   ____kasan_slab_free+0x143/0x1b0
   kmem_cache_free+0xe3/0x4d0
   cifs_small_buf_release+0x29/0x90
   SMB2_negotiate+0x8b7/0x1c60
   smb2_negotiate+0x51/0x70
   cifs_negotiate_protocol+0xf0/0x160
   cifs_get_smb_ses+0x5fa/0x13c0
   mount_get_conns+0x7a/0x750
   cifs_mount+0x103/0xd00
   cifs_smb3_do_mount+0x1dd/0xcb0
   smb3_get_tree+0x1d5/0x300
   vfs_get_tree+0x41/0xf0
   path_mount+0x9b3/0xdd0
   __x64_sys_mount+0x190/0x1d0
   do_syscall_64+0x35/0x80
   entry_SYSCALL_64_after_hwframe+0x46/0xb0

The UAF is because:

 mount(pid: 921)               | cifsd(pid: 923)
-------------------------------|-------------------------------
                               | cifs_demultiplex_thread
SMB2_negotiate                 |
 cifs_send_recv                |
  compound_send_recv           |
   smb_send_rqst               |
    wait_for_response          |
     wait_event_state      [1] |
                               |  standard_receive3
                               |   cifs_handle_standard
                               |    handle_mid
                               |     mid->resp_buf = buf;  [2]
                               |     dequeue_mid           [3]
     KILL the process      [4] |
    resp_iov[i].iov_base = buf |
 free_rsp_buf              [5] |
                               |   is_network_name_deleted [6]
                               |   callback

1. After send request to server, wait the response until
    mid->mid_state != SUBMITTED;
2. Receive response from server, and set it to mid;
3. Set the mid state to RECEIVED;
4. Kill the process, the mid state already RECEIVED, get 0;
5. Handle and release the negotiate response;
6. UAF.

It can be easily reproduce with add some delay in [3] - [6].

Only sync call has the problem since async call's callback is
executed in cifsd process.

Add an extra state to mark the mid state to READY before wakeup the
waitter, then it can get the resp safely.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-52572?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2023-52572?

Apply the vendor's patch.

## Is CVE-2023-52572 being exploited?

There is no known exploitation of CVE-2023-52572 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-52572 and fix it if it is affected.

What it is: CVE-2023-52572 is a high-severity use after free vulnerability in Debian Debian Linux, published on 2 Mar 2024. 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-2023-52572 in the wild and no public exploit code.

Affected product: Debian Debian 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-2023-52572/ (Markdown: https://insights.sbomify.com/CVE-2023-52572/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52572
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52572
- OSV: https://osv.dev/vulnerability/CVE-2023-52572

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52572/
Summaries are generated and may contain mistakes; the official description above is the record.