---
id: CVE-2026-89438
title: 'platform/x86: ISST: Validate logical CPU id and clos id'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  platform/x86: ISST: Validate logical CPU id and clos id

  Validate max CLOS ID and logical CPU ID for core power feature.
  Reject any clos level or logical CPU number gre…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe:
  - CWE-787
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    0d601126c7afda9bb94dfecc8b2c0a16f20d76cb
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    c9ee2770eb95ba316a56d776b2b66666b70c194b
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    5b032e1dda486ca41d10536bd195bd8a559af1e2
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    82d4afadb02fb4d7d7bb9230900904c10e49ec87
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    124e2dbabe460c2a6e7440f4ad8af560131295c9
  - Linux 6.4
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:46:46.711Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89438'
references:
  - url: 'https://git.kernel.org/stable/c/0d601126c7afda9bb94dfecc8b2c0a16f20d76cb'
  - url: 'https://git.kernel.org/stable/c/c9ee2770eb95ba316a56d776b2b66666b70c194b'
  - url: 'https://git.kernel.org/stable/c/5b032e1dda486ca41d10536bd195bd8a559af1e2'
  - url: 'https://git.kernel.org/stable/c/82d4afadb02fb4d7d7bb9230900904c10e49ec87'
  - url: 'https://git.kernel.org/stable/c/124e2dbabe460c2a6e7440f4ad8af560131295c9'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89438.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89438'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532236'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89438'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89438'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89438.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00206
epssPercentile: 0.10479
ingestedAt: '2026-09-14T15:23:07.454Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

platform/x86: ISST: Validate logical CPU id and clos id

Validate max CLOS ID and logical CPU ID for core power feature.
Reject any clos level or logical CPU number greater than the
supported maximum. These are used to calculate MMIO offset.

## Affected

- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 0d601126c7afda9bb94dfecc8b2c0a16f20d76cb`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < c9ee2770eb95ba316a56d776b2b66666b70c194b`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 5b032e1dda486ca41d10536bd195bd8a559af1e2`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 82d4afadb02fb4d7d7bb9230900904c10e49ec87`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 124e2dbabe460c2a6e7440f4ad8af560131295c9`
- `Linux 6.4`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89438.json)