Microsoft CVE-2026-26156

This vulnerability (CWE-122: Heap-based Buffer Overflow) resides in the Windows Hyper-V hypervisor, Microsoft's Type-1 virtualization platform that provides hardware-level isolation for virtual machines. Heap-based buffer overflows occur when a program writes data beyond the allocated memory boundary in the heap, potentially corrupting adjacent memory structures and enabling control-flow hijacking. In Hyper-V's context, the vulnerability likely exists in guest-to-host communication channels, VM configuration parsing, or resource management routines where untrusted input from virtual machines or local processes interacts with heap-allocated buffers. The CVSS vector PR:N (No Privileges Required) indicates the flaw can be triggered without authenticated system access, though UI:R (User Interaction Required) suggests social engineering or a secondary trigger mechanism is necessary. The affected CPE strings confirm impact across Windows 10 (versions 1607, 1809, 21H2, 22H2), Windows 11 (22H3, 23H2, 24H2, 25H2, 26H1), and Windows Server editions (2016, 2019, 2022, 2025) including Server Core installations, indicating the vulnerable code exists in core Hyper-V components shared across these platforms.