# CVE-2026-98635: scsi: block: Fix zones_cond out-of-bounds write on zone report

> A malicious SCSI device can trigger an out-of-bounds write in the Linux kernel, potentially leading to code execution or system crash.

- **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:** DEBIAN-CVE-2026-98635, GHSA-xmm2-hmmq-mgf4, UBUNTU-CVE-2026-98635

## What is CVE-2026-98635?

CVE-2026-98635 is a memory corruption 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: block: Fix zones_cond out-of-bounds write on zone report

blk_revalidate_disk_zones() sizes the zones_cond array from the disk
capacity and zone size, but the index used by blk_revalidate_zone_cond()
comes from the device-driven report_zones() walk and is never checked
against the array size. A device reporting more zones than fit the array
makes blk_zone_set_cond() write out of bounds.

One way to reach this is a zone count exceeding 32 bits: both
blk_revalidate_zone_args.nr_zones and struct zoned_disk_info.nr_zones are
unsigned int, so a disk advertising more than UINT_MAX zones (e.g.  2^32 +
1024 zones of one 512-byte logical block) gets its zone count truncated to
a small value, undersizing the array while the report walk keeps counting
upward.

Check the index against the array size before storing the zone condition,
and refuse to revalidate when the zone count does not fit 32 bits.

## Which versions are affected by CVE-2026-98635?


## How do I fix CVE-2026-98635?

Apply the vendor's patch.

## Is CVE-2026-98635 being exploited?

There is no known exploitation of CVE-2026-98635 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98635 and fix it if it is affected.

What it is: CVE-2026-98635 is a memory corruption 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-2026-98635 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-2026-98635/ (Markdown: https://insights.sbomify.com/CVE-2026-98635/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98635
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98635
- OSV: https://osv.dev/vulnerability/CVE-2026-98635

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98635/
Summaries are generated and may contain mistakes; the official description above is the record.