What is a buffer overflow vulnerability?

A buffer overflow is a type of software vulnerability that happens when a program writes more data to a memory buffer than it can hold. This extra data can spill over into adjacent memory, potentially overwriting valid data or injecting malicious code. Attackers exploit buffer overflows to crash programs, corrupt data, or execute arbitrary code—often gaining control of the system. It’s a common flaw in poorly written code, especially in languages like C and C++ that don’t automatically check memory boundaries.