Bug 2482555 (CVE-2026-46131)

Summary: CVE-2026-46131 kernel: KVM: x86: check for nEPT/nNPT in slow flush hypercalls
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) x86 virtualization module. An incorrect check for nested EPT/NPT (Nested Extended Page Tables/Nested Nested Page Tables) in slow flush hypercalls could lead to improper handling of L2 guests. This vulnerability arises because the `is_guest_mode(vcpu)` check was not sufficient, potentially allowing an L2 guest with nested EPT/NPT enabled to bypass intended security restrictions.
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Description OSIDB Bzimport 2026-05-28 11:03:05 UTC
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.