CVE-2026-25121: apko has a path traversal in apko dirFS which allows filesystem writes outside base

A Path Traversal vulnerability was discovered in apko’s dirFS filesystem abstraction. An attacker who can supply a malicious APK package (e.g., via a compromised or typosquatted repository) could create directories or symlinks outside the intended installation root. The MkdirAll, Mkdir, and Symlink methods in pkg/apk/fs/rwosfs.go use filepath.Join() without validating that the resulting path stays within the base directory.

Fix: Fixed by d8b7887. Merged into release.

Acknowledgements

apko thanks Oleh Konko from 1seal for discovering and reporting this issue.