The defective logic in the Linux kernel's mshv_vtl register-page handling allows a NULL pointer dereference when a CPU's register page is not allocated but the global flag still indicates presence. During a user-space memory fault the kernel dereferences a NULL per-CPU register page, triggering a VM_FAULT_SIGBUS that aborts the process and causes a local denial of service. This issue is a classic NULL pointer dereference (CWE‑476) and is limited to scenarios where register-page setup is only partially successful across online CPUs. An attacker can exploit it by inducing a fault within the vulnerable mapping; no elevated privileges or remote access are required, and the resulting SIGBUS leads to abrupt termination of the affected application.

Vendors: Linux kernel. Products: The Linux kernel subsystem implementing mshv_vtl register pages. Version information is not specified in the advisory; the flaw applies to any kernel build that contains the unsanitised check within mshv_vtl_configure_reg_page and mshv_vtl_fault.

The EPSS score is not available and the vulnerability is not listed in the CISA KEV catalog. No CVSS figure is provided, but the flaw can cause a SIGBUS and local process termination, which is a significant impact for production workloads. The likely attack vector is a local fault trigger by a user-space application interacting with the VTL register mapping; it does not require remote code execution or network interaction.