In OCaml-tar before 3.4.0, a crafted archive with ../ path segments in its name allows escaping the current working directory. This is not desired behavior, and tar(1) rejects such extractions, but ocaml-tar decompresses it anyway. The impact is that it allows arbitrary file writes outside of the desired extraction directory (to an attacker that can reach a tar decompression endpoint).
CWE-22