# CVE-2026-98585: eth: fbnic: Avoid rounding zero ring sizes

> A local attacker can cause a denial of service in the fbnic network driver by triggering undefined behavior with zero ring sizes.

- **Severity:** Not scored
- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98585, DEBIAN-CVE-2026-98585, GHSA-pmrp-mw94-3ww9, UBUNTU-CVE-2026-98585

## What is CVE-2026-98585?

CVE-2026-98585 is a denial of service vulnerability in Linux, published on 18 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:

eth: fbnic: Avoid rounding zero ring sizes

roundup_pow_of_two() is undefined for zero. ethtool permits a zero ring
size to reach the driver, where the minimum-size check should reject it.

Leave zero unchanged while rounding nonzero ring sizes. The minimum-size
check then rejects zero deterministically without changing the established
behavior for other values.

## Which versions are affected by CVE-2026-98585?


## How do I fix CVE-2026-98585?

Apply the vendor's patch.

## Is CVE-2026-98585 being exploited?

There is no known exploitation of CVE-2026-98585 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98585 and fix it if it is affected.

What it is: CVE-2026-98585 is a denial of service vulnerability in Linux, published on 18 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-2026-98585 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-2026-98585/ (Markdown: https://insights.sbomify.com/CVE-2026-98585/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98585
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98585
- OSV: https://osv.dev/vulnerability/CVE-2026-98585

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98585/
Summaries are generated and may contain mistakes; the official description above is the record.