Stack-based Buffer Overflow

This vulnerability happens when functions like `strcpy`, `gets`, or `scanf` are used without proper bounds checking. Since the buffer is allocated as a local variable within a function, the overflow overwrites other critical data on the stack, such as saved register values, function parameters, and most importantly, the return address. By carefully crafting the excess data, an attacker can redirect execution to malicious code they've injected or to existing code that benefits their attack, leading to a complete compromise. To prevent this, developers should always use secure, length-limited alternatives (like `strncpy` or `snprintf`) and perform explicit bounds checking before any write operation. Enabling compiler protections like stack canaries, address space layout randomization (ASLR), and non-executable stacks can also mitigate exploitation, but the primary defense is writing safe, validated code that never trusts unchecked input.