Linux Kernel Vulnerability Affecting Hyper-V on Memory Access Permissions

CVE-2026-43096

What is CVE-2026-43096?

A vulnerability in the Linux kernel's handling of memory access permissions within Hyper-V can lead to infinite fault loops when guest machines attempt to access memory regions without the necessary permissions. The issue arises in the mshv_handle_gpa_intercept function, which currently tries to remap pages for all types of access faults. If a guest writes to a read-only region, the remap occurs unsuccessfully, causing the guest virtual CPU to enter an endless fault loop. By validating access types against memory region permissions before allowing remapping, the vulnerability can be mitigated, preventing potential denial-of-service attacks where malicious guests could exploit the weakness to exhaust host resources.

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