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PatchSiren cyber security CVE debrief

CVE-2026-46032 Linux CVE debrief

A vulnerability in the Linux kernel's KVM nested virtualization (nSVM) subsystem could allow a malicious L2 guest to cause the host to continue execution with corrupted state. When loading L1's CR3 fails during a nested #VMEXIT, the nested_svm_vmexit() function previously returned an error code that was ignored by most callers, causing the hypervisor to continue running L1 with invalid state rather than triggering a shutdown as hardware would. The fix injects a triple fault to emulate hardware shutdown behavior and removes the return value to ensure consistent error handling.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-06-16
Advisory published
2026-05-27
Advisory updated
2026-06-16

Who should care

Organizations running Linux KVM with nested virtualization enabled on AMD processors, cloud providers offering nested virtualization services, and security teams monitoring hypervisor integrity

Technical summary

The vulnerability exists in KVM's nested SVM implementation where nested_svm_vmexit() could fail to restore L1's CR3 during nested guest exit. Rather than causing a shutdown as AMD hardware specifies, the error return was ignored and execution continued with corrupted state. The resolution injects a triple fault to match hardware behavior and removes the problematic return value path.

Defensive priority

high

Recommended defensive actions

  • Apply kernel patches from stable branches (5d291ef0585ed880ed4dd71ea1a5965e0a65fb53, 9a738cf170a4a2332ea3a15e23ec65b5757fe4a1)
  • Update to latest stable Linux kernel with KVM fixes
  • Audit systems running nested virtualization with AMD SVM
  • Monitor for unexpected guest shutdowns or triple faults as potential exploitation indicators

Evidence notes

The CVE description and kernel commit references confirm this is a resolved vulnerability in KVM's nested SVM (AMD virtualization) implementation. The fix aligns guest behavior with AMD hardware specification (APM) which mandates shutdown on illegal host state load during #VMEXIT.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46032 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46032

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46032 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46032

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/5d291ef0585ed880ed4dd71ea1a5965e0a65fb53

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9a738cf170a4a2332ea3a15e23ec65b5757fe4a1

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.