CVE-2026-86071: Junrar: LocalFolderExtractor mkdir escape allows directory creation outside extraction root

LocalFolderExtractor validates only the final canonical file path before extraction. However, makeFile() creates intermediate directories one path segment at a time without checking whether each created directory remains inside the destination folder.

A malicious RAR entry can make the final file path resolve inside the extraction destination, while causing intermediate mkdir() calls to create attacker-chosen directories outside the extraction root.

This is an extraction root escape via unchecked intermediate directory creation. The default impact is directory creation outside the intended destination, not unconditional arbitrary file content write.