# CVE-2025-38488: smb: client: fix use-after-free in crypt_message when using async crypto

> A use-after-free in the Linux kernel SMB client causes crashes when hardware crypto accelerators are used, requiring a patch to restore async handling.

- **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:** 28 Jul 2025
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-73458, BELL-CVE-2025-38488, DEBIAN-CVE-2025-38488, GHSA-8gh3-6693-hwj4, ROOT-OS-DEBIAN-11-CVE-2025-38488, ROOT-OS-DEBIAN-12-CVE-2025-38488, ROOT-OS-UBUNTU-2204-CVE-2025-38488, ROOT-OS-UBUNTU-2404-CVE-2025-38488, UBUNTU-CVE-2025-38488

## What is CVE-2025-38488?

CVE-2025-38488 is a critical use after free vulnerability in Debian Debian Linux, published on 28 Jul 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: fix use-after-free in crypt_message when using async crypto

The CVE-2024-50047 fix removed asynchronous crypto handling from
crypt_message(), assuming all crypto operations are synchronous.
However, when hardware crypto accelerators are used, this can cause
use-after-free crashes:

  crypt_message()
    // Allocate the creq buffer containing the req
    creq = smb2_get_aead_req(..., &req);

    // Async encryption returns -EINPROGRESS immediately
    rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req);

    // Free creq while async operation is still in progress
    kvfree_sensitive(creq, ...);

Hardware crypto modules often implement async AEAD operations for
performance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS,
the operation completes asynchronously. Without crypto_wait_req(),
the function immediately frees the request buffer, leading to crashes
when the driver later accesses the freed memory.

This results in a use-after-free condition when the hardware crypto
driver later accesses the freed request structure, leading to kernel
crashes with NULL pointer dereferences.

The issue occurs because crypto_alloc_aead() with mask=0 doesn't
guarantee synchronous operation. Even without CRYPTO_ALG_ASYNC in
the mask, async implementations can be selected.

Fix by restoring the async crypto handling:
- DECLARE_CRYPTO_WAIT(wait) for completion tracking
- aead_request_set_callback() for async completion notification
- crypto_wait_req() to wait for operation completion

This ensures the request buffer isn't freed until the crypto operation
completes, whether synchronous or asynchronous, while preserving the
CVE-2024-50047 fix.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-38488?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38488?

Apply the vendor's patch.

## Is CVE-2025-38488 being exploited?

There is no known exploitation of CVE-2025-38488 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-2025-38488 and fix it if it is affected.

What it is: CVE-2025-38488 is a critical use after free vulnerability in Debian Debian Linux, published on 28 Jul 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-2025-38488 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-2025-38488/ (Markdown: https://insights.sbomify.com/CVE-2025-38488/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38488
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38488
- OSV: https://osv.dev/vulnerability/CVE-2025-38488

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38488/
Summaries are generated and may contain mistakes; the official description above is the record.