What Does Buffer Overflow Mean?

A buffer overflow occurs when more data are written to a buffer than it can hold. The excess data is written to the adjacent memory, overwriting the contents of that location and causing unpredictable results in a program. Buffer overflows happen when there is improper validation (no bounds prior to the data being written. It is considered a bug or weakness in the software

Techopedia Explains Buffer Overflow

Attackers can exploit a buffer overflow bug by injecting code that is specifically tailored to cause buffer overflow with the initial part of a data set, then writing the rest of the data to the memory address adjacent to the overflowing buffer. The overflow data might contain executable code that allows the attackers to run bigger and more sophisticated programs or grant themselves access to the system.