Systems & Memory
Buffer Overflow
Also: buffer overrun, stack overflow bug
Writing more data into a fixed-size block of memory than it can hold, so the extra lands in neighbouring memory.
In more detail
The classic cause is copying input without checking its size. Results range from a crash to altered data to a changed return address that lets attacker-supplied data steer the program. Fixes are explicit size checks, safer functions and memory-safe languages. Classified as CWE-787 when it writes out of bounds.