CVE-2026-64562
Description
A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) nested virtualization (nVMX) feature. This vulnerability occurs because the shadow Virtual Machine Control Structure (VMCS) is freed prematurely while still being referenced. Due to asynchronous operations, a virtual CPU (vCPU) might attempt to execute a VMCLEAR instruction on the freed memory page. This timing issue could lead to system instability or a denial of service for the host system.
Mitigation
To mitigate this vulnerability, disable nested virtualization (nVMX) if it is not required. For Intel processors, add `options kvm_intel nested=0` to a new configuration file like `/etc/modprobe.d/disable-nested-kvm.conf`. For AMD processors, use `options kvm_amd nested=0`. A system reboot or reloading the `kvm_intel` or `kvm_amd` kernel module is required for the change to take effect. Disabling nested virtualization may impact virtual machine functionality that relies on this feature.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 8.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
