UndefinedBehaviorSanitizer¶ Introduction¶ UndefinedBehaviorSanitizer (UBSan) is a fast undefined behavior detector. UBSan modifies the program at compile-time to catch various kinds of undefined behavior during program execution, for example: Array subscript out of bounds, where the bounds can be statically determined Bitwise shifts that are out of bounds for their data type Dereferencing misalign