---
id: CVE-2026-80554
title: 's390/vfio_ccw: Limit the number of channel program segments'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/vfio_ccw: Limit the number of channel program segments

  The processing of channel programs, and the CCWs within them, is done
  recursively. As such, there is an arb…
severity: critical
cvss: 9.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c <
    15fb4559a7fdf0b8725e433a71cfd03a1313a48b
  - >-
    Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c <
    a1625f66eaa1200068a0e2c05bc90e65182fc4e3
  - >-
    Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c <
    06f4d6e5a8af6c2072e8cd39dbc512c683ca7fb2
  - >-
    Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c <
    4ee94790490ae8dcc97df8597f07836c8a81bbcf
  - >-
    Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c <
    5405c90d6a47b3014e74ee0618a162449abbbc93
  - Linux 4.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T19:17:23.132592Z'
published: '2026-08-26'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:26:26.790Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80554'
references:
  - url: 'https://git.kernel.org/stable/c/15fb4559a7fdf0b8725e433a71cfd03a1313a48b'
  - url: 'https://git.kernel.org/stable/c/a1625f66eaa1200068a0e2c05bc90e65182fc4e3'
  - url: 'https://git.kernel.org/stable/c/06f4d6e5a8af6c2072e8cd39dbc512c683ca7fb2'
  - url: 'https://git.kernel.org/stable/c/4ee94790490ae8dcc97df8597f07836c8a81bbcf'
  - url: 'https://git.kernel.org/stable/c/5405c90d6a47b3014e74ee0618a162449abbbc93'
tags:
  - cve.org
epss: 0.00196
epssPercentile: 0.08642
ingestedAt: '2026-10-16T19:46:24.315Z'
---

## Overview

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

s390/vfio_ccw: Limit the number of channel program segments

The processing of channel programs, and the CCWs within them, is done
recursively. As such, there is an arbitrary (but not architectural)
limit to the number of CCWs that can exist in a single channel program.

The vfio-ccw logic breaks these channel programs into segments whenever
it encounters a Transfer-In-Channel (TIC) CCW, and the combined number
of segments count towards the global limit. Impose an equivalent limit
to the number of segments until such logic can be made non-recursive.

## Affected

- `Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 15fb4559a7fdf0b8725e433a71cfd03a1313a48b`
- `Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < a1625f66eaa1200068a0e2c05bc90e65182fc4e3`
- `Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 06f4d6e5a8af6c2072e8cd39dbc512c683ca7fb2`
- `Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 4ee94790490ae8dcc97df8597f07836c8a81bbcf`
- `Linux >= 0a19e61e6d4c6192077ead760ba0a2d350987d4c < 5405c90d6a47b3014e74ee0618a162449abbbc93`
- `Linux 4.12`

## Remediation

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