Zip Slip is an archive-based path traversal flaw. It happens when software extracts a ZIP or similar archive and trusts the file names inside it. A crafted entry such as ../../etc/passwd or an absolute path can make extraction write files outside the intended folder, overwriting application files, startup scripts, or web content.
This matters because archive handling appears in installers, updaters, backup tools, and document processors, so a single bug can lead to file overwrite, persistence, or code execution. Defenders prevent Zip Slip by normalizing paths before writing, rejecting absolute and parent-directory segments, and enforcing a strict destination root. In secure code reviews and testing, archive extraction is a common place to look for this mistake.