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CVE-2026-46076: KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1

highCVSS 7CVE-2026-46076

CSIRTS triage

vendor: Linuxproduct: Linux kernelDenial of servicePrivilege escalation
What
KVM nSVM does not raise an undefined opcode exception for unhandled VMMCALL instructions not intercepted by L1.
Who is affected
Nested virtualization deployments using AMD-V with nested virtual machine support.
Urgency
High; improper exception handling in nested virtualization can affect guest isolation.
Action
Update to a patched Linux kernel version with KVM nSVM VMMCALL handling fix.

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Details

Source
Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity
high — CVSS 7
Published
2026-08-06
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-46076

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-46076coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for KVM

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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