CVE-2026-29870: Improper Limitation of a Pathname to a Restricted Directory

A directory traversal vulnerability in the agentic-context-engine project versions up to 0.7.1 allows arbitrary file writes via the checkpoint_dir parameter in OfflineACE.run. The save_to_file method in ace/skillbook.py fails to normalize or validate filesystem paths, allowing traversal sequences to escape the intended checkpoint directory. This vulnerability allows attackers to overwrite arbitrary files accessible to the application process, potentially leading to application corruption, privilege escalation, or code execution depending on the deployment context.