CVE-2026-54550: IzPack has Path Traversal in UnpackerBase that allows writing files outside the installation directory via malicious pack entries

IzPack’s UnpackerBase.unpack() resolves pack-file target paths without any canonical-path or directory-containment check. An attacker who distributes a trojanized installer JAR (the format is unsigned) can include pack entries whose targetPath contains ../ sequences. When a victim runs the installer the file is written to an attacker-chosen location on disk under the victim’s privileges — including startup folders, PATH directories, or system locations.