CVE-2026-89931
Description
A flaw was found in the Kernel-based Virtual Machine (KVM) nVMX component of the Linux kernel. This vulnerability arises from improper handling of nested virtual machine (VM) exits, where a specific request flag is not consistently cleared. This oversight can lead to the same memory pages being mapped twice, a form of memory corruption. A malicious guest virtual machine could exploit this to cause system instability, leading to a denial of service, or potentially gain unauthorized access to sensitive information.
Statement
KVM nVMX may fail to clear KVM_REQ_GET_NESTED_STATE_PAGES when CONFIG_KVM_HYPERV is disabled because the request check was compiled only under the Hyper V path. A nested guest workflow can then leave the request pending across a nested VM Exit and later VMLAUNCH or VMRESUME, which may double map vmcs12 related pages. For the CVSS the PR:L is used because an attacker needs local ability to use KVM and run a nested virtualization workload, but full host administrative privileges are not necessarily required in common /dev/kvm group based deployments. The issue is not network reachable and is triggered through local KVM ioctls and guest execution rather than packet traffic. Impact is primarily denial of service or resource exhaustion from repeated page mapping or reference retention. No concrete arbitrary write, UAF, or information leak primitive is visible from this patch, so confidentiality and integrity remain none for the grounded score.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 4.7 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality
Technical Impact: Modify Application Data; Read Application Data
If a released resource is subsequently reused or reallocated, then an attempt to use the original resource might allow access to sensitive data that is associated with a different user or entity.
Other,Availability
Technical Impact: Other; DoS: Crash, Exit, or Restart
When a resource is released it might not be in an expected state, later attempts to access the resource may lead to resultant errors that may lead to a crash.
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