---
id: CVE-2026-64558
title: 's390/pkey: Check length in pkey_pckmo handler implementation'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/pkey: Check length in pkey_pckmo handler implementation

  Explicitly check the length of the target buffer in the pkey_pckmo
  implementation of the key_to_protkey() …
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
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 <
    02028a24e26d85262ab9c8fc4344e1f3503007fc
  - >-
    Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 <
    433e5e70cdc1edf382d28d08a885b22e2b98b7da
  - >-
    Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 <
    614aa0491c7a190556c2345dddee0b6f5ed90989
  - >-
    Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 <
    1ac287e2af9a9112fe271427ef45eceb26bce8b4
  - Linux 6.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:42:40.566840Z'
published: '2026-07-29'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:52:52.698Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64558'
references:
  - url: 'https://git.kernel.org/stable/c/02028a24e26d85262ab9c8fc4344e1f3503007fc'
  - url: 'https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da'
  - url: 'https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989'
  - url: 'https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4'
tags:
  - cve.org
epss: 0.0012
epssPercentile: 0.01678
ingestedAt: '2026-10-16T17:24:46.834Z'
---

## Overview

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

s390/pkey: Check length in pkey_pckmo handler implementation

Explicitly check the length of the target buffer in the pkey_pckmo
implementation of the key_to_protkey() handler function. The handler
function fails, if the generated output data exceeds the length of the
provided target buffer.

## Affected

- `Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 < 02028a24e26d85262ab9c8fc4344e1f3503007fc`
- `Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 < 433e5e70cdc1edf382d28d08a885b22e2b98b7da`
- `Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 < 614aa0491c7a190556c2345dddee0b6f5ed90989`
- `Linux >= 8fcc231ce3bea12b78bb94b280cdc03cff342435 < 1ac287e2af9a9112fe271427ef45eceb26bce8b4`
- `Linux 6.12`

## Remediation

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