Buffer overflows remain the leading cause of software vulnerabilities in the world of information security. The proposed segment-based non-executable stack approach aims to prevent the injection and execution of arbitrary code in an existing process's stack space under Windows NT/2000 and Intel 32-bit CPUs. The application's user-mode stack is relocated to the higher address and the effective limit of the code segment excludes the relocated stack from the code segment. The segmentation logic of IA-32 processors monitors the accesses to the memory ranges and a page fault is generated if instruction fetches are initiated in the stack memory pages. It is highly effective in preventing both known and yet unknown stack smashing attacks.