Linux Kernel mshv_vtl Null Deref on mmap due to missing reg-page
CVE-2026-99168 Published on October 28, 2026
mshv_vtl: Check per-CPU register page before mmap
In the Linux kernel, the following vulnerability has been resolved:
mshv_vtl: Check per-CPU register page before mmap
Register-page setup is optional for each CPU. If allocation or
registration fails, mshv_vtl_configure_reg_page() warns and leaves that
CPU's reg_page NULL, but initial context setup continues successfully.
Meanwhile, successful setup on another CPU sets the global
mshv_has_reg_page flag.
mshv_vtl_fault() checks this global flag before selecting the requested
CPU's register page. With mixed setup results across online CPUs, the
check passes even for a CPU with no register page, reaching
get_page(NULL) when userspace faults in that mapping.
Check the selected per-CPU register page before taking its reference and
return VM_FAULT_SIGBUS if it is absent.
Products Associated with CVE-2026-99168
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Affected Versions
Linux:- Version 7bfe3b8ea6e30437e01fcb8e4f56ef6e4d986d0f and below 5c0757b065fbd140d8fbd05dc2c2146b713dfa68 is affected.
- Version 7bfe3b8ea6e30437e01fcb8e4f56ef6e4d986d0f and below 874194a8de75fc2f4d1fb70c670b289b7e48f93e is affected.
- Version 6.19 is affected.
- Before 6.19 is unaffected.
- Version 7.2.13, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.