# CVE-2026-98390: x86/amd_node: Avoid divide by zero on virtualized systems

> A divide-by-zero error in the Linux kernel x86/amd_node module causes a crash on virtualized systems, leading to denial of service.

- **Severity:** Not scored
- **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:** 14 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98390, DEBIAN-CVE-2026-98390, GHSA-fx97-gm68-7q96, UBUNTU-CVE-2026-98390

## What is CVE-2026-98390?

CVE-2026-98390 is a denial of service vulnerability in Linux, published on 14 Oct 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:

x86/amd_node: Avoid divide by zero on virtualized systems

On a virtualized system, the number of nodes does not have a relationship to
the number of roots.  A Xen PVH dom0 can calculate roots_per_node as 0, which
crashes with a divide by zero in:

  if (count++ % roots_per_node)

because the underlying topology code on Xen ends up making num_nodes
2 and num_roots 1 and the integer division result is 0.

The issue is seen with Xen, but it could affect other systems.

Set roots_per_node to 1 in this case. Print a firmware bug when this is
performed for non-virtualized systems.

  [ bp: Massage commit message. ]

## Which versions are affected by CVE-2026-98390?


## How do I fix CVE-2026-98390?

Apply the vendor's patch.

## Is CVE-2026-98390 being exploited?

There is no known exploitation of CVE-2026-98390 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98390 and fix it if it is affected.

What it is: CVE-2026-98390 is a denial of service vulnerability in Linux, published on 14 Oct 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-2026-98390 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-2026-98390/ (Markdown: https://insights.sbomify.com/CVE-2026-98390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98390
- OSV: https://osv.dev/vulnerability/CVE-2026-98390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98390/
Summaries are generated and may contain mistakes; the official description above is the record.