CVE-2026-80554
Received Received - Intake

s390/vfio_ccw Channel Program Segment Limit Bypass

Publication date: 2026-08-26

Last updated on: 2026-08-26

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-08-26
Last Modified
2026-08-26
Generated
2026-08-26
AI Q&A
2026-08-26
EPSS Evaluated
N/A
NVD
CVE-2026-80554
EUVD
EUVD-2026-66469

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a limit on the number of channel program segments processed by the s390/vfio_ccw driver. Channel programs are broken into segments when a Transfer-In-Channel (TIC) CCW is encountered, and the total segments count toward a global limit. The issue arises because the processing is done recursively, which can lead to an arbitrary limit being exceeded.

Impact Analysis

This vulnerability may cause system instability or crashes if the limit on channel program segments is exceeded. It could lead to denial-of-service conditions or unexpected behavior in systems using the s390/vfio_ccw driver, particularly in mainframe environments.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the s390/vfio_ccw channel program segment limit issue.

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