# CVE-2025-40065: RISC-V: KVM: Write hgatp register with valid mode bits

> A Linux kernel KVM bug on RISC-V systems writes invalid bits to the hgatp register, potentially causing system instability or crashes.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Oct 2025
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-68924, BELL-CVE-2025-40065, DEBIAN-CVE-2025-40065, GHSA-m7w6-fmw8-2v8x, ROOT-OS-DEBIAN-12-CVE-2025-40065, ROOT-OS-DEBIAN-13-CVE-2025-40065, ROOT-OS-UBUNTU-2404-CVE-2025-40065, UBUNTU-CVE-2025-40065

## What is CVE-2025-40065?

CVE-2025-40065 is a vulnerability in Linux, published on 28 Oct 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:

RISC-V: KVM: Write hgatp register with valid mode bits

According to the RISC-V Privileged Architecture Spec, when MODE=Bare
is selected,software must write zero to the remaining fields of hgatp.

We have detected the valid mode supported by the HW before, So using a
valid mode to detect how many vmid bits are supported.

## Which versions are affected by CVE-2025-40065?


## How do I fix CVE-2025-40065?

Apply the vendor's patch.

## Is CVE-2025-40065 being exploited?

There is no known exploitation of CVE-2025-40065 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40065 and fix it if it is affected.

What it is: CVE-2025-40065 is a vulnerability in Linux, published on 28 Oct 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-2025-40065 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-2025-40065/ (Markdown: https://insights.sbomify.com/CVE-2025-40065/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40065
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40065
- OSV: https://osv.dev/vulnerability/CVE-2025-40065

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40065/
Summaries are generated and may contain mistakes; the official description above is the record.