---
id: CVE-2026-89442
title: 'platform/x86: ISST: Validate socket ID in clos_assoc ioctl'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  platform/x86: ISST: Validate socket ID in clos_assoc ioctl

  isst_if_clos_assoc() validates the user-supplied socket_id with
  'socket_id > topology_max_packages()', but i…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-476
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    c847ea4851ecfa3462cc711ded2c3c3dd8d08ab8
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    0d90ab5f80e19cddfeb0c9fab47a1f34aa932075
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    207b4dc6eb100141b122b2602504a1429a4b6558
  - >-
    Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e <
    a89f07db0cb95c54dac4a8406c79a04e44a73c3c
  - Linux 6.4
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:46:51.770Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89442'
references:
  - url: 'https://git.kernel.org/stable/c/c847ea4851ecfa3462cc711ded2c3c3dd8d08ab8'
  - url: 'https://git.kernel.org/stable/c/0d90ab5f80e19cddfeb0c9fab47a1f34aa932075'
  - url: 'https://git.kernel.org/stable/c/82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca'
  - url: 'https://git.kernel.org/stable/c/207b4dc6eb100141b122b2602504a1429a4b6558'
  - url: 'https://git.kernel.org/stable/c/a89f07db0cb95c54dac4a8406c79a04e44a73c3c'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89442.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89442'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532359'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89442'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89442'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89442.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00168
epssPercentile: 0.06065
scores:
  cna: 7.8
  vendor: 5.5
ingestedAt: '2026-09-14T15:23:07.453Z'
---

## Overview

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

platform/x86: ISST: Validate socket ID in clos_assoc ioctl

isst_if_clos_assoc() validates the user-supplied socket_id with
'socket_id > topology_max_packages()', but isst_common.sst_inst[] is
allocated with topology_max_packages() entries, so the valid index range
is [0, topology_max_packages()).  The '>' comparison lets
socket_id == topology_max_packages() pass and index one entry past the
array.

In addition, isst_common.sst_inst[socket_id] is NULL for an in-range
package that has no bound TPMI SST instance, and the pointer is used
without a NULL check.  Both the out-of-bounds entry and the NULL pointer
are then dereferenced by map_partition_power_domain_id() and the
following power_domain_info access.

Reject socket_id >= topology_max_packages() and a NULL sst_inst, matching
the checks already performed by get_instance().

## Affected

- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < c847ea4851ecfa3462cc711ded2c3c3dd8d08ab8`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 0d90ab5f80e19cddfeb0c9fab47a1f34aa932075`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 207b4dc6eb100141b122b2602504a1429a4b6558`
- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < a89f07db0cb95c54dac4a8406c79a04e44a73c3c`
- `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-2026-89442.json)