KVM: s390: Fix memory corruption by not reinjecting CK machine checks (CVE-2026-89920) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89920

KVM: s390: Fix memory corruption by not reinjecting CK machine checks

Answer in brief

CVE-2026-89920 records a Unknown severity vulnerability in KVM: s390: Fix memory corruption by not reinjecting CK machine checks. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 16, 2026Updated Sep 16, 2026Source checked Sep 16, 2026First seen by HOL Sep 16, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=4d62fcc0b692e3b4058d7d138114c27cd8b011f7 <6ee52d3af2a1bf70349cf3f860933c8d221e229a \|\| >=4d62fcc0b692e3b4058d7d138114c27cd8b011f7 <7077ec953996acc04b49d1dfc43df1c1a2a74395 \|\| >=4d62fcc0b692e3b4058d7d138114c27cd8b011f7 <546dde823a36d7283dcf46127c2f3d093443860f	6ee52d3af2a1bf70349cf3f860933c8d221e229a, 7077ec953996acc04b49d1dfc43df1c1a2a74395, 546dde823a36d7283dcf46127c2f3d093443860f
Linux/Linuxgeneric	4.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 6ee52d3af2a1bf70349cf3f860933c8d221e229a if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 16, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix memory corruption by not reinjecting CK machine checks Channel-subsystem damage machine checks are for the host channel subsystem. The guest channel subsystem is emulated in the userspace VMM. There is no point in forwarding such machine checks into the guest. This also simplifies the machine check reinjection and avoids kfree of a stack variable as reported by sashiko. There might be still machine checks that have the ck bit set with another bit (like instruction damage), mask out the CK bit in s390_backup_mcck_info(), like the CP and ED bits already are.

Quoted source text, attributed separately from HOL analysis.