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CVE Record

CVE-2026-46131: KVM: x86: check for nEPT/nNPT in slow flush hypercalls

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel KVM x86 issue in nested virtualization handling. The public record says KVM used the wrong condition before translating a nested guest address during slow flush hypercalls. Business risk is unclear because no CVSS, CWE, impact statement, or exploitation report is provided.

Executive priority

Treat as a targeted virtualization-platform patching item, not a broad emergency from current evidence. Prioritize environments hosting nested virtualization or untrusted VM workloads, and monitor vendor advisories for severity clarification.

Technical view

The fix changes KVM x86 slow flush hypercall logic to check for nested EPT/NPT rather than only is_guest_mode(vcpu). The source states translate_nested_gpa() is valid only when an L2 guest runs with nested EPT/NPT enabled, so the previous guard was too broad.

Likely exposure

Likely exposure is Linux x86 KVM systems using affected kernel versions or commit ancestry, especially where nested virtualization is enabled. The bundle does not identify affected distributions, cloud platforms, or tenant-accessible configurations.

Exploitation context

The source bundle does not report active exploitation, public exploit availability, or KEV listing. It also does not describe attacker prerequisites or concrete impact, so exploitation context remains incomplete.

Researcher notes

Key uncertainty is impact. The record documents a correctness fix around nested GPA translation gating, but not the failure mode, privilege boundary, crash potential, or guest-to-host implications. Further analysis should compare the stable commits and affected branch context.

Mitigation direction

  • Apply the relevant Linux stable kernel fix for your maintained branch.
  • Check your distribution or kernel vendor advisory for backported fixes.
  • Prioritize KVM hosts that allow nested virtualization workloads.
  • Avoid direct wrangler-style assumptions; verify vendor guidance before operational workarounds.

Validation and detection

  • Inventory Linux KVM x86 hosts and current kernel build versions.
  • Check whether nested virtualization is enabled or offered to workloads.
  • Map deployed kernels to the affected and fixed stable references.
  • Confirm vendor packages include one of the referenced upstream fixes.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-46131 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxaee738236dca0d0870789138ec494e15d6303566, aee738236dca0d0870789138ec494e15d6303566, aee738236dca0d0870789138ec494e15d6303566, aee738236dca0d0870789138ec494e15d6303566, aee738236dca0d0870789138ec494e15d6303566unaffected
LinuxLinux6.2, 0, 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1affected
Weakness

CWE details

No CWE listed

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