KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping (CVE-2026-89917) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89917

KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping

Answer in brief

CVE-2026-89917 records a Unknown severity vulnerability in KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping. 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	>=7270cc9157f474dfc46750a34c9d7defc686b2eb <5cbd8761d001c11ada73b1753d772c4745a70e72 \|\| >=7270cc9157f474dfc46750a34c9d7defc686b2eb <9065c1261f8a05c6a7a2d90048c7c0665ab2896d \|\| >=7270cc9157f474dfc46750a34c9d7defc686b2eb <38640bc32be3fcf9526d477155bc19d3f146231f	5cbd8761d001c11ada73b1753d772c4745a70e72, 9065c1261f8a05c6a7a2d90048c7c0665ab2896d, 38640bc32be3fcf9526d477155bc19d3f146231f
Linux/Linuxgeneric	6.16	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 5cbd8761d001c11ada73b1753d772c4745a70e72 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: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page. The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set. These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects. Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race. Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.

Quoted source text, attributed separately from HOL analysis.