CVE-2026-89915

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Remove VM-wide VNCR mapping counter The global VNCR mapping counter is used to decide whether an L1 provided VNCR page is mapped in L0 on any CPU at the point of dealing with a TLB invalidation. It is incremented when a mapping is made in the fixmap, and decremented when unmapped. As it turns out, this tracking has several flaws: - we are trying to invalidate TLBs, and the mapping is only an opportunistic consequence of the TLB. Checking this counter to decide whether a TLB needs to be invalidated may result in missed invalidations. - an L1 vcpu invalidating its own TLB (a very likely case) will not succeed in invalidating the VNCR pseudo TLB because that page is not mapped in L0 at this stage. Given that this tracking fails at delivering the minimum guarantees that are required and is only a performance optimisation, remove it completely.

CVSS v3 9.3 CRITICAL

9.3^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 2.5 / Impact : 6.0

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope CHANGED

References

Link	Resource
https://git.kernel.org/stable/c/5453b85c7ebb605febac3df42021f9471663f051
https://git.kernel.org/stable/c/87c2bbf189829dce4aaada8f82e3d54ccc037976
https://git.kernel.org/stable/c/c55bc773b6e814406658fae7dc5c15f639ed816e

Configurations

No configuration.

History

16 Sep 2026, 15:18

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.3

Information

Published : 2026-09-16 11:17

Updated : 2026-09-16 15:18

NVD link : CVE-2026-89915

Mitre link : CVE-2026-89915

CVE.ORG link : CVE-2026-89915

JSON object : View

Products Affected

No product.

CWE

No CWE.

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