---
id: CVE-2026-74515
title: 'KVM: s390: pci: Reject adapter interrupt forwarding if already enabled'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

  The MPCIFC instruction doesn't allow registering adapter interrupts without
  first unregistering.…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    642d2d1067f7c4d753ae0e3ba5bc98b43cfe3c70
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    78d9648e7e960546d5b72504a0b0358cd8bb1e9d
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    6be1ff49ba81f96a6fa55915e6d920be43ac57cc
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    6837f0ae85fd54cf64c8a0c7c530bba2fae0a207
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    591952b63a9f976da7d49f719f36ec826ee2a575
  - >-
    Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc <
    8fa01be5a6149404adb82c0979a78f6347edd3ef
  - Linux 6.0
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:58:46.342564Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:51.934Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74515'
references:
  - url: 'https://git.kernel.org/stable/c/642d2d1067f7c4d753ae0e3ba5bc98b43cfe3c70'
  - url: 'https://git.kernel.org/stable/c/78d9648e7e960546d5b72504a0b0358cd8bb1e9d'
  - url: 'https://git.kernel.org/stable/c/6be1ff49ba81f96a6fa55915e6d920be43ac57cc'
  - url: 'https://git.kernel.org/stable/c/6837f0ae85fd54cf64c8a0c7c530bba2fae0a207'
  - url: 'https://git.kernel.org/stable/c/591952b63a9f976da7d49f719f36ec826ee2a575'
  - url: 'https://git.kernel.org/stable/c/8fa01be5a6149404adb82c0979a78f6347edd3ef'
tags:
  - cve.org
epss: 0.00129
epssPercentile: 0.0227
ingestedAt: '2026-10-16T19:46:24.350Z'
---

## Overview

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

KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

The MPCIFC instruction doesn't allow registering adapter interrupts without
first unregistering. So reject any request to enable interrupt forwarding
if its already enabled for the zPCI device. This also fixes overwriting and
thus leaking resources when the ioctl is called multiple times for the same
device.

## Affected

- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 642d2d1067f7c4d753ae0e3ba5bc98b43cfe3c70`
- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 78d9648e7e960546d5b72504a0b0358cd8bb1e9d`
- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 6be1ff49ba81f96a6fa55915e6d920be43ac57cc`
- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 6837f0ae85fd54cf64c8a0c7c530bba2fae0a207`
- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 591952b63a9f976da7d49f719f36ec826ee2a575`
- `Linux >= 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc < 8fa01be5a6149404adb82c0979a78f6347edd3ef`
- `Linux 6.0`

## Remediation

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