# CVE-2026-64438: crypto: qat - fix VF2PF work teardown race in adf_disable_sriov()

> A race condition in the Linux kernel QAT driver allows a use-after-free during SR-IOV teardown, potentially causing system crashes or arbitrary code execution.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** 25 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-64438, DEBIAN-CVE-2026-64438, GHSA-j99q-5p83-43j8, ROOT-OS-DEBIAN-12-CVE-2026-64438, ROOT-OS-DEBIAN-13-CVE-2026-64438, ROOT-OS-UBUNTU-2204-CVE-2026-64438, UBUNTU-CVE-2026-64438

## What is CVE-2026-64438?

CVE-2026-64438 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 2026. 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:

crypto: qat - fix VF2PF work teardown race in adf_disable_sriov()

The VF2PF interrupt handler queues PF-side response work that stores a
raw pointer to per-VF state (struct adf_accel_vf_info). Currently,
adf_disable_sriov() destroys per-VF mutexes and frees vf_info without
stopping new VF2PF work or waiting for in-flight workers to complete. A
concurrently scheduled or already queued worker can then dereference
freed memory.

This manifests as a use-after-free when KASAN is enabled:

  BUG: KASAN: null-ptr-deref in mutex_lock+0x76/0xe0
  Write of size 8 at addr 0000000000000260 by task kworker/24:2/...
  Workqueue: qat_pf2vf_resp_wq adf_iov_send_resp [intel_qat]
  Call Trace:
    kasan_report+0x119/0x140
    mutex_lock+0x76/0xe0
    adf_gen4_pfvf_send+0xd4/0x1f0 [intel_qat]
    adf_recv_and_handle_vf2pf_msg+0x290/0x360 [intel_qat]
    adf_iov_send_resp+0x8c/0xe0 [intel_qat]
    process_one_work+0x6ac/0xfd0
    worker_thread+0x4dd/0xd30
    kthread+0x326/0x410
    ret_from_fork+0x33b/0x670

Add a PF-local flag, vf2pf_disabled, that gates work queueing, worker
processing, and interrupt re-enabling during teardown. Set this flag
atomically with the hardware interrupt mask inside
adf_disable_all_vf2pf_interrupts(). After masking, synchronize the AE
cluster MSI-X interrupt and flush the PF response workqueue before
tearing down per-VF locks and state so all in-flight work completes
before vf_info is destroyed.

Introduce adf_enable_all_vf2pf_interrupts() to clear the flag and
unmask all VF2PF interrupts under the same lock when SR-IOV is
re-enabled. This ensures the software flag and hardware state transition
atomically on both the enable and disable paths.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-64438?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64438?

Apply the vendor's patch.

## Is CVE-2026-64438 being exploited?

There is no known exploitation of CVE-2026-64438 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-2026-64438 and fix it if it is affected.

What it is: CVE-2026-64438 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 2026. 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-2026-64438 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-2026-64438/ (Markdown: https://insights.sbomify.com/CVE-2026-64438/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64438
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64438
- OSV: https://osv.dev/vulnerability/CVE-2026-64438

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64438/
Summaries are generated and may contain mistakes; the official description above is the record.