CVE-2016-4020: The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which...

Security readout for executives and security teams

This is a QEMU/KVM virtualization information leak. A privileged administrator inside a guest VM could cause QEMU to expose data from the host process stack. It is most relevant where guests are untrusted, customer-controlled, or separated by tenant boundaries. Exposure is likely limited to environments running affected QEMU/KVM i386 virtual APIC code with users who have administrator control inside guest operating systems. The source bundle does not provide precise affected version ranges. Handle during normal vulnerability remediation, with higher priority for shared virtualization platforms or customer-managed guests. Business impact is confidentiality risk to host memory, but public evidence here does not support emergency active-exploitation handling. Mitigation focus: Apply QEMU security updates from the relevant operating system vendor.; Check the upstream QEMU fix for imm32 initialization.; Prioritize hosts running untrusted or multi-tenant guest workloads..

Prepared

Jun 13, 2026, 14:22 UTC (UTC+00:00)

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