CVE-2025-21872 is a vulnerability in the Linux kernel's EFI mokvar table handling. The kernel previously mapped the entire mokvar table repeatedly to determine its size, which could fail and cause a kernel warning and traceback if the table was large. The flaw was due to limitations in early_memmap() and unnecessary full-table mapping. The fix changes the code to map only each entry header individually and enforces NUL termination of variable names.