# CVE-2025-39932: smb: client: let smbd_destroy() call disable_work_sync(&info->post_send_credits_work)

> A race condition in the Linux kernel SMB client allows use-after-free, potentially causing a system crash or denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Oct 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-68154, AZL-75327, BELL-CVE-2025-39932, DEBIAN-CVE-2025-39932, GHSA-ww7h-mcjr-5643, ROOT-OS-DEBIAN-11-CVE-2025-39932, ROOT-OS-DEBIAN-12-CVE-2025-39932, ROOT-OS-DEBIAN-13-CVE-2025-39932, ROOT-OS-UBUNTU-2204-CVE-2025-39932, ROOT-OS-UBUNTU-2404-CVE-2025-39932, UBUNTU-CVE-2025-39932

## What is CVE-2025-39932?

CVE-2025-39932 is a critical use after free vulnerability in Linux kernel, published on 4 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

smb: client: let smbd_destroy() call disable_work_sync(&info->post_send_credits_work)

In smbd_destroy() we may destroy the memory so we better
wait until post_send_credits_work is no longer pending
and will never be started again.

I actually just hit the case using rxe:

WARNING: CPU: 0 PID: 138 at drivers/infiniband/sw/rxe/rxe_verbs.c:1032 rxe_post_recv+0x1ee/0x480 [rdma_rxe]
...
[ 5305.686979] [    T138]  smbd_post_recv+0x445/0xc10 [cifs]
[ 5305.687135] [    T138]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 5305.687149] [    T138]  ? __kasan_check_write+0x14/0x30
[ 5305.687185] [    T138]  ? __pfx_smbd_post_recv+0x10/0x10 [cifs]
[ 5305.687329] [    T138]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[ 5305.687356] [    T138]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 5305.687368] [    T138]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 5305.687378] [    T138]  ? _raw_spin_unlock_irqrestore+0x11/0x60
[ 5305.687389] [    T138]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 5305.687399] [    T138]  ? get_receive_buffer+0x168/0x210 [cifs]
[ 5305.687555] [    T138]  smbd_post_send_credits+0x382/0x4b0 [cifs]
[ 5305.687701] [    T138]  ? __pfx_smbd_post_send_credits+0x10/0x10 [cifs]
[ 5305.687855] [    T138]  ? __pfx___schedule+0x10/0x10
[ 5305.687865] [    T138]  ? __pfx__raw_spin_lock_irq+0x10/0x10
[ 5305.687875] [    T138]  ? queue_delayed_work_on+0x8e/0xa0
[ 5305.687889] [    T138]  process_one_work+0x629/0xf80
[ 5305.687908] [    T138]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 5305.687917] [    T138]  ? __kasan_check_write+0x14/0x30
[ 5305.687933] [    T138]  worker_thread+0x87f/0x1570
...

It means rxe_post_recv was called after rdma_destroy_qp().
This happened because put_receive_buffer() was triggered
by ib_drain_qp() and called:
queue_work(info->workqueue, &info->post_send_credits_work);

## Which versions are affected by CVE-2025-39932?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39932?

Apply the vendor's patch.

## Is CVE-2025-39932 being exploited?

There is no known exploitation of CVE-2025-39932 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-39932 and fix it if it is affected.

What it is: CVE-2025-39932 is a critical use after free vulnerability in Linux kernel, published on 4 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-39932 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-39932/ (Markdown: https://insights.sbomify.com/CVE-2025-39932/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39932
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39932
- OSV: https://osv.dev/vulnerability/CVE-2025-39932

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39932/
Summaries are generated and may contain mistakes; the official description above is the record.