Destination escape is a file-handling flaw where data meant for one target directory is written somewhere else. Instead of landing inside the intended container, archive, or copy destination, the operation escapes that boundary and reaches another path on the same system.
This matters because attackers can use it to overwrite sensitive files, plant code, or move data from an isolated context into the host filesystem. It often appears in copy, extract, or import features that trust user-controlled paths, symbolic links, or malformed filenames. Defenses include strict path normalization, rejecting traversal sequences, resolving links safely, comparing the final resolved path to an allowed base directory, and running the operation with least privilege. In secure code review, any file-transfer workflow should be treated as a boundary-crossing risk, not a simple utility command.