# CVE-2024-39483: KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

> A logic error in KVM SVM vNMI handling triggers a kernel warning when NMIs are masked, potentially causing a denial of service in virtualized environments.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Jul 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-43270, BELL-CVE-2024-39483, DEBIAN-CVE-2024-39483, GHSA-jx29-mm4x-qpqh, UBUNTU-CVE-2024-39483

## What is CVE-2024-39483?

CVE-2024-39483 is a high-severity denial of service vulnerability in Linux kernel, published on 5 Jul 2024. 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:

KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

When requesting an NMI window, WARN on vNMI support being enabled if and
only if NMIs are actually masked, i.e. if the vCPU is already handling an
NMI.  KVM's ABI for NMIs that arrive simultanesouly (from KVM's point of
view) is to inject one NMI and pend the other.  When using vNMI, KVM pends
the second NMI simply by setting V_NMI_PENDING, and lets the CPU do the
rest (hardware automatically sets V_NMI_BLOCKING when an NMI is injected).

However, if KVM can't immediately inject an NMI, e.g. because the vCPU is
in an STI shadow or is running with GIF=0, then KVM will request an NMI
window and trigger the WARN (but still function correctly).

Whether or not the GIF=0 case makes sense is debatable, as the intent of
KVM's behavior is to provide functionality that is as close to real
hardware as possible.  E.g. if two NMIs are sent in quick succession, the
probability of both NMIs arriving in an STI shadow is infinitesimally low
on real hardware, but significantly larger in a virtual environment, e.g.
if the vCPU is preempted in the STI shadow.  For GIF=0, the argument isn't
as clear cut, because the window where two NMIs can collide is much larger
in bare metal (though still small).

That said, KVM should not have divergent behavior for the GIF=0 case based
on whether or not vNMI support is enabled.  And KVM has allowed
simultaneous NMIs with GIF=0 for over a decade, since commit 7460fb4a3400
("KVM: Fix simultaneous NMIs").  I.e. KVM's GIF=0 handling shouldn't be
modified without a *really* good reason to do so, and if KVM's behavior
were to be modified, it should be done irrespective of vNMI support.

## Which versions are affected by CVE-2024-39483?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-39483?

Apply the vendor's patch.

## Is CVE-2024-39483 being exploited?

There is no known exploitation of CVE-2024-39483 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-2024-39483 and fix it if it is affected.

What it is: CVE-2024-39483 is a high-severity denial of service vulnerability in Linux kernel, published on 5 Jul 2024. 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-2024-39483 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-2024-39483/ (Markdown: https://insights.sbomify.com/CVE-2024-39483/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39483
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39483
- OSV: https://osv.dev/vulnerability/CVE-2024-39483

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-39483/
Summaries are generated and may contain mistakes; the official description above is the record.