---
id: "CVE-2026-98635"
kind: "vulnerability"
aliases: ["CVE-2026-98635"]
title: "Linux kernel: zoned block devices can write past zone condition array"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "runtime", "storage", "zoned-block-devices"]
not_affected_if: ["no-zoned-devices"]
published_at: "2026-10-18T16:17:16+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:21:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98635", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: zoned block devices can write past zone condition array

The Linux kernel's zone revalidation code can write past the end of the zones_cond array when a device reports more zones than the array was sized for, including counts that overflow 32 bits. The sources do not state what an attacker gets beyond an out-of-bounds kernel write.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `uname -r` and compare against the kernel version that carries the upstream fix, which the sources do not name
- Check whether zoned block devices (SMR or ZNS drives) are attached with `lsblk -z`

## Fix

- Update the Linux kernel to a release that includes the upstream commit 'scsi: block: Fix zones_cond out-of-bounds write on zone report' (version unknown from sources)

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98635

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_