KVM x86 Nested EPT/NPT Validation Flaw

Publication date: 2026-05-28

Last updated on: 2026-06-24

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: check for nEPT/nNPT in slow flush hypercalls Checking is_guest_mode(vcpu) is incorrect, because translate_nested_gpa() is only valid if an L2 guest is running *with nested EPT/NPT enabled*. Instead use the same condition as translate_nested_gpa() itself.

CVSS Scores

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Meta Information

Published

2026-05-28

Last Modified

2026-06-24

Generated

2026-07-07

AI Q&A

2026-05-28

EPSS Evaluated

2026-07-06

NVD

CVE-2026-46131

EUVD

EUVD-2026-32890

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	7.1
linux	linux_kernel	7.1
linux	linux_kernel	From 6.13 (inc) to 6.18.30 (exc)
linux	linux_kernel	From 6.19 (inc) to 7.0.7 (exc)
linux	linux_kernel	From 6.7 (inc) to 6.12.88 (exc)
linux	linux_kernel	From 6.2 (inc) to 6.6.140 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Linux kernel's KVM (Kernel-based Virtual Machine) component for x86 architectures. It involves an incorrect check for nested Extended Page Tables (nEPT) or nested Nested Page Tables (nNPT) during slow flush hypercalls. Specifically, the code incorrectly uses the is_guest_mode(vcpu) check, which is not valid unless an L2 guest is running with nested EPT/NPT enabled. The correct approach is to use the same condition as the translate_nested_gpa() function itself.

Impact Analysis

This vulnerability relates to the Linux kernel's KVM module for x86 architectures, specifically in the handling of nested virtualization with EPT/NPT (Extended Page Tables/Nested Page Tables). An incorrect check for nested page table usage could potentially lead to improper memory translation in nested guests, which might cause unexpected behavior or security issues in virtualized environments.

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