# CVE-2025-40166: drm/xe/guc: Check GuC running state before deregistering exec queue

> A missing state check in the Linux kernel's Xe GPU driver causes a null dereference and kernel warning when unbinding a running exec queue.

- **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:** 12 Nov 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-40166, DEBIAN-CVE-2025-40166, GHSA-v9hw-4wx3-7mqf, ROOT-OS-DEBIAN-13-CVE-2025-40166, ROOT-OS-UBUNTU-2404-CVE-2025-40166, UBUNTU-CVE-2025-40166

## What is CVE-2025-40166?

CVE-2025-40166 is a high-severity vulnerability in Linux, published on 12 Nov 2025. 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:

drm/xe/guc: Check GuC running state before deregistering exec queue

In normal operation, a registered exec queue is disabled and
deregistered through the GuC, and freed only after the GuC confirms
completion. However, if the driver is forced to unbind while the exec
queue is still running, the user may call exec_destroy() after the GuC
has already been stopped and CT communication disabled.

In this case, the driver cannot receive a response from the GuC,
preventing proper cleanup of exec queue resources. Fix this by directly
releasing the resources when GuC is not running.

Here is the failure dmesg log:
"
[  468.089581] ---[ end trace 0000000000000000 ]---
[  468.089608] pci 0000:03:00.0: [drm] *ERROR* GT0: GUC ID manager unclean (1/65535)
[  468.090558] pci 0000:03:00.0: [drm] GT0:     total 65535
[  468.090562] pci 0000:03:00.0: [drm] GT0:     used 1
[  468.090564] pci 0000:03:00.0: [drm] GT0:     range 1..1 (1)
[  468.092716] ------------[ cut here ]------------
[  468.092719] WARNING: CPU: 14 PID: 4775 at drivers/gpu/drm/xe/xe_ttm_vram_mgr.c:298 ttm_vram_mgr_fini+0xf8/0x130 [xe]
"

v2: use xe_uc_fw_is_running() instead of xe_guc_ct_enabled().
    As CT may go down and come back during VF migration.

(cherry picked from commit 9b42321a02c50a12b2beb6ae9469606257fbecea)

## Which versions are affected by CVE-2025-40166?


## How do I fix CVE-2025-40166?

Apply the vendor's patch.

## Is CVE-2025-40166 being exploited?

There is no known exploitation of CVE-2025-40166 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40166 and fix it if it is affected.

What it is: CVE-2025-40166 is a high-severity vulnerability in Linux, published on 12 Nov 2025. 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-2025-40166 in the wild and no public exploit code.

Affected product: 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-2025-40166/ (Markdown: https://insights.sbomify.com/CVE-2025-40166/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40166
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40166
- OSV: https://osv.dev/vulnerability/CVE-2025-40166

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40166/
Summaries are generated and may contain mistakes; the official description above is the record.