Glossary

Buffer overflow

Writing past the end, or before the start, of a buffer, which corrupts adjacent memory (CWE-120; out-of-bounds writes are CWE-787, with CWE-121 and CWE-122 for stack and heap buffers). In C and C++ it can overwrite return addresses, function pointers or allocator metadata; bounds-checked APIs, sanitizers in testing and memory-safe languages prevent it.

Also called: buffer overrun · heap overflow · heap-based buffer overflow · stack-based buffer overflow · out-of-bounds write
Defined in: MITRE CWE-120
Identifiers: CWE-120: Classic buffer overflow · CWE-787: Out-of-bounds write · CWE-121: Stack-based buffer overflow · CWE-122: Heap-based buffer overflow

Covered in

Guide

Find, fix and contain memory-safety bugs in C and C++

Recognize out-of-bounds access, use after free, NULL dereference and integer overflow in C and C++, fix them with checked lengths and single ownership, harden release builds, catch the rest with sanitizers and fuzzing, and plan new code in a memory-safe language.

Practice: Buffer over-read lab: Stop a heartbeat over-read