# CVE-2026-98634: scsi: sd_zbc: Reject disks with too many zones

> A malicious SCSI device can cause integer overflows in the Linux kernel's ZBC driver, leading to inconsistent resource allocation and potential 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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109230, BELL-CVE-2026-98634, DEBIAN-CVE-2026-98634, GHSA-gc5v-q6x9-gww4, UBUNTU-CVE-2026-98634

## What is CVE-2026-98634?

CVE-2026-98634 is a 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:

scsi: sd_zbc: Reject disks with too many zones

sd_zbc_read_zones() computes the number of zones with 64-bit arithmetic and
stores the result in the unsigned int nr_zones field of struct
zoned_disk_info, silently truncating counts that exceed 32 bits. The
truncated count is later used to size per-zone resources, while the device
may still report more zones than fit.

Moreover, sd_zbc_report_zones() counts the reported zones with a signed int
zone_idx, which overflows past INT_MAX. Reject devices reporting more than
INT_MAX zones at scan time; such a device is not realistic for any medium
that exists today, and accepting it produces inconsistent zone bookkeeping.

## Which versions are affected by CVE-2026-98634?


## How do I fix CVE-2026-98634?

Apply the vendor's patch.

## Is CVE-2026-98634 being exploited?

There is no known exploitation of CVE-2026-98634 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98634 and fix it if it is affected.

What it is: CVE-2026-98634 is a 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-2026-98634 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-2026-98634/ (Markdown: https://insights.sbomify.com/CVE-2026-98634/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98634
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98634
- OSV: https://osv.dev/vulnerability/CVE-2026-98634

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98634/
Summaries are generated and may contain mistakes; the official description above is the record.