# CVE-2025-40336: drm/gpusvm: fix hmm_pfn_to_map_order() usage

> A flaw in the Linux kernel GPU SVM driver allows mapping memory outside intended ranges, potentially leading to memory corruption and privilege escalation.

- **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:** 9 Dec 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-40336, DEBIAN-CVE-2025-40336, GHSA-5gqx-mjr7-rp8x, ROOT-OS-DEBIAN-12-CVE-2025-40336, ROOT-OS-DEBIAN-13-CVE-2025-40336, ROOT-OS-UBUNTU-2204-CVE-2025-40336, ROOT-OS-UBUNTU-2404-CVE-2025-40336, UBUNTU-CVE-2025-40336

## What is CVE-2025-40336?

CVE-2025-40336 is a high-severity memory corruption vulnerability in Linux, published on 9 Dec 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/gpusvm: fix hmm_pfn_to_map_order() usage

Handle the case where the hmm range partially covers a huge page (like
2M), otherwise we can potentially end up doing something nasty like
mapping memory which is outside the range, and maybe not even mapped by
the mm. Fix is based on the xe userptr code, which in a future patch
will directly use gpusvm, so needs alignment here.

v2:
  - Add kernel-doc (Matt B)
  - s/fls/ilog2/ (Thomas)

## Which versions are affected by CVE-2025-40336?


## How do I fix CVE-2025-40336?

Apply the vendor's patch.

## Is CVE-2025-40336 being exploited?

There is no known exploitation of CVE-2025-40336 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40336 and fix it if it is affected.

What it is: CVE-2025-40336 is a high-severity memory corruption vulnerability in Linux, published on 9 Dec 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-2025-40336 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-2025-40336/ (Markdown: https://insights.sbomify.com/CVE-2025-40336/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40336
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40336
- OSV: https://osv.dev/vulnerability/CVE-2025-40336

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40336/
Summaries are generated and may contain mistakes; the official description above is the record.