Linux Kernel Vulnerability Affects Hypervisor Functionality

CVE-2026-99258

What is CVE-2026-99258?

A vulnerability exists in the Linux kernel relating to how the hypervisor handles per-CPU output pages during hypercalls, particularly in environments with SEV-SNP CoCo VMs. The hv_apicid_to_vp_index() function is improperly managing memory allocation, leading to potential security risks. By sharing the input page for both reading and writing, the kernel mitigates the need for additional memory allocations, which could pose a problem in larger virtual CPU configurations. This flaw has been resolved, ensuring enhanced stability and security in system operations.

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